If the FPS is too low, Minecraft will close without saving any chunks. The inventory, player position, momentum, and time will all be maintained, however, as these are stored in the level.dat and are constantly updated.
If Minecraft crashes, your world may revert back to an older save from the last time you saved & quit.
Occasionally, the level.dat file is re-written, causing you to lose your held items, and generate a new spawn. Also occurs in SMP.
You are unable to directly swap items in your inventory if the two items are same. This is important if you would like to swap the same item type with two different durability values. This is a result of the way combining stacks works.
Sometimes you can see through everything; this randomly happens on all games on all platforms. Toggling the fog distance will change everything back to normal (Default key is F).
When you open up the achievements interface at night, wherever in the sky there is not a cloud, the sky will be white.
While viewing the achievements interface, the world is not paused. Everything can move, as if opening the inventory.
Occasionally, picked up items will not appear in the inventory.
Sometimes, the game may reset the seed that the map generates from. This is a result of tweaks of the seed and terrain generation code that are regular parts of the game's updates.
If you are sneaking when you exit the game, when you reload the game you fall into the block below you, and onto the block below it instead.
The red glow featured at sunset and sunrise is normally a gradient. Pulling up the player's inventory will cause the gradient to solidify along a sharp boundary.
If you hold the left mouse button down while holding a item, then open your inventory, still holding the left mouse button, and then close your inventory, as long as you don't release the left mouse button, you are able to break blocks without the swinging item animation.
Occasionally, when saving the game and reloading, you will fall through the block you were standing on. This can be prevented by jumping as soon as the game loads.
A bug exists where the game may refuse to remember custom controls after updating (not to a specific version - just updating in general). This is caused by one of the values in Minecraft's "options.txt" file being unset, usually the "lastServer" field - attempting to connect to any multi-player server address (valid or otherwise) typically resolves the problem.
Occasionally, some chunks of the map do not update with the day/night cycle, as seen here. Also, even in caves or closed environments the player can still see lighting bugs, (i.e. An area has full light and it has a small spot of full darkness next to it. When the spot is edited, it changes to normal.) These glitches are fairly common and can cause multiple problems. Usually staring in the general direction of the chunk for a moment will fix this.
If you enter Fullscreen mode, then exit it, mouse clicks will no longer work for game dialogs (game menu, inventory etc.). However, mining and using items still work. Pressing Esc, waiting for the game to save and restarting the client or re-entering fullscreen to save and quit resolves this problem. Here is a topic on Minecraft Forums related to this bug.
If you hit a movement key and at the same time open inventory or click that movement key will become "stuck". Pressing and releasing the same movement key again will stop you again.
If you disconnect from a server while a message is displayed, and then load a single player world, the text will appear in SSP as shown here.
Sometimes mobs within a certain area will stop moving, and entering the area will cause the player to become rooted to the spot and often vibrate wildly. Many animations, such as digging and health recovery will be broken, and mobs that the player hits will constantly loop the damage animation without dying. It is not possible to catch fire.
If the player adjusts their system clock one hour forward, the game will run abnormally fast, allowing quick movement and mining. Changing the time back, exiting the game, setting the time forward again, and re-entering the game will allow you to change the system clock properly. Note that the inverse of this is not true--setting the time backwards will not slow down the game.
The openAL32.dll and openAL64.dll that come with Minecraft do not work properly. This sometimes causes Minecraft to crash when players turn sound on in the options menu. On Windows machines, deleting Minecraft's openAL files usually solves the problem, because Minecraft will then automatically use Windows operating system's copy of the openAL dll, which works properly.
Selection bounding box breaks ATI card's Anti-aliasing. [1]
Sometimes Smooth Lighting dosen't work in water
Smooth Lighting acts weird on certain blocks like signs, doors, and other special blocks
If you are playing Minecraft and computer suddenly shuts down, you will lose your world
While sleeping, particles (torches, furnaces, etc.) do not "adjust" to face you, some of them may look flat or even be invisible.
Beds placed in fully enclosed (on both sides and with only one space above) areas can cause you to wake up inside a wall, killing you and potentially destroying your items.
Beds cannot be placed on snow.
Putting a Powered Rail in the front of your bed will make it so when you wake up it will still be night, as if you never went to sleep. (Only tested with the powered rail on)
Boats will collide with a snow layer as if it is a full block when placed on land.
If you manage to stand on your boat while it is under water, the boat will be unable to move. The boat will still retain horizontal movement, though, and will often slide out from underneath you.
If you go under a water stream your boat will accelerate and rise upwards. This is an error in the programming of how boats float.
If you save and reload while in a boat, you will no longer be in the boat.
You can, although slowly, move in your boat on land.
Pressing F5 whilst in a boat will show your leg/foot armor protruding from the bottom of the boat, even though your character is sitting. The leg armor will also fail to properly adjust to still be around the player's legs and will still be going straight down as if the player was standing still.
If you place a boat on the ground and drop sand onto it, the sand will repeat the falling animation on the top of the boat and you will be able to pass through it. Reloading the world will properly place the sand, but the boat may be dark as if it's in an area with no light.
Exiting a boat will make the player to fall through it. This could be fixed by implementing code that would place the player one block higher than the boat when it's exited.
Cactus also has a South/West rule for applying damage. Placing a block above a single cactus piece prevents you from stepping on the cactus and prevents you from taking damage by pushing against the south or west sides of the cactus. The north and east sides of the cactus can still hurt you.
If there is snow, fire, water, or lava on a block, then a cactus can be placed on top of that block violating the usual rules for placing cactus. When the cactus grows it will recognize that it is improperly planted and uproot itself leaving two loose cactus blocks.
If you place a door next to a Cactus it will break and drop them both, but the door will drop two doors instead of one as shown Here. This can be reproduced indefinitely.
If a door is placed level with the cactus it will break the cactus and the bottom part of the door, leaving a un-collectible but breakable window.
'Double doors' do not open simultaneously as one might expect them to when activated with redstone.
Occasionally, placed fences will become invisible under certain conditions: if there are no actual blocks within a pre-defined 16-block-high layer of a chunk, any fences placed within will be invisible.
Fire has a South/West rule for applying damage. Placing a block directly above a fire prevents you from stepping into the fire and also makes it impossible to damage yourself by pressing against the block from the south or west sides. The north and east sides of the fire can still hurt you.
It is possible to have "Invisible Fire", fire that is dark and unlit.
A forest fire can cause strange patches of light to be left after all the fire has burnt out.
When destroying a Furnace, unlike Chests, anything inside the Furnace will be permanently destroyed.
Furnaces emit light even if its face side is blocked. This is because the block itself emits the light, and it could be fixed by making the block in front of it emit light instead.
Gravel or sand will not fall down if a non-solid block is placed between the time a block underneath is destroyed and before the sand/gravel begins to fall. Example
Gravel or sand will accumulate into resources if a non-solid block is placed between the time a block underneath is destroyed and during the time the sand/gravel is falling to fill in the spot. Example
If you break a block below gravel or sand and are walking into gravel or sand, you will literally walk into the gravel or sand.
If you allow sand or gravel to fall on you, after moving around it is possible to be in such a position that you will not suffocate and you will be able to see through the sand or gravel and any blocks connected to the sand or gravel. This can reveal caverns.
If you place a sand or gravel block then quit the game before it starts falling, upon reload, it will float. If a nearby block updates, it will fall.
When sand or gravel is generated above a cave (or any opening), it will float until a space by it is modified in any way.
If the player moves into a corner to their southwest of which lava is on the other side, the player will be damaged(see South/West rule). This same bug can also incinerate items and other entities.
Levers can be placed on the bottom of a block, as long as there is an open space, and a block horizontal to the open space. The lever will act as if placed on the horizontal block, but looks glitched, as shown here.
Placing a lever on snow will produce a similar effect.
When spawning mine carts on a small track, they will gain momentum from colliding with each other.
Riding a minecart at the top of the map makes the player invisible until you leave the cart or ride downwards.
Sometimes moving minecarts disappear completely.
Riding a minecart into a Nether portal causes the game to crash and kills the player.
Removing a minecart while riding in it will cause the player to go through the ground.
Minecarts can go off tracks or crash through the ground if their momentum is too high.
When exiting a minecart, if there is only a single block free above the track, the player will take some damage.
If you start sneaking right after destroying a minecart, you may crash and get buried, but there is also a chance you will get multiple minecart drops.
When exiting Minecarts when there is a block in front, the user may rarely glitch into the block directly underneath the Minecart and appear to be walking inside of that one block with the upper torso the only part showing until the user jumps out of the block.
If a mob is riding a minecart and 2 or more mine carts get stuck in each other, after destroying or moving the carts away from the other carts the mobs will be invisible.
When up close to a Zombie Pigman, the inventory GUI will become much brighter. This could be interpreted as a "hint" towards future trading/interaction with some mobs.
If you are above a Ghast's height and are standing still, Ghasts will shoot fireballs over your head, without damaging you.
Ghasts will shoot at the camera in 3rd person view.
Squids can spawn in unintended locations, such as from cavern springs or even in The Nether(if water is hacked in). This is more common in multiplayer.
Mobs can move briefly before map data is loaded when signing out and loading the world, usually resulting in the mobs getting stuck.
Tamed Wolves will attack you if you shoot yourself with an arrow. This can be achieved by looking straight up, shooting an arrow, and moving forward a small bit to compensate for a small amount of curve.
If a wolf is tamed when it's attacking an another mob, it may still attack it when on sitting animation.
Placing a boat in the portal and entering it will cause the game to crash .
Similarly, riding a minecart or a pig into a Nether portal will cause the game to crash.
Being killed in the Nether will cause a portal to be generated near your relative location on Earth, as though you had teleported back from the location at which you died normally.Can someone confirm this?
Dying while in the Nether will also ignore a changed spawn point (via sleeping).
Opening the inventory then crafting while in a portal will destroy the item you are crafting and make the loading screen text turn gray, will add an identically gray "shadow" beneath the text, and will prevent the loading bar from filling. Everything will load as normal, though.
If the game is closed while entering The Nether, you will be sent to your spawn point on earth without held items, as if you were killed. However, it ignores a when the player's spawnpoint is changed via sleeping.
If snow, fire, water, or lava are over a block, a sapling may be placed on that block even if it is not a dirt block. After a short time the sapling will recognize that it is illegally planted and uproot itself.
If a block is covered in snow, fire, water, or lava, sugar cane can be placed on that block violating the usual placement rules for sugar cane. When the sugar cane grows it will recognize that it is illegally planted and uproot itself leaving two loose sugar cane blocks.
Bugs in the terrain generation code can cause Sugar Cane to float.
Utilizing snow, one can place saplings, cacti, and sugarcane on any block. However, the cacti and sugarcane will break when they first grow, and the sapling will uproot itself after a while.
In snow biomes, water and lava lakes can generate below the snow and leave some of the snow floating.
When firing arrows at the opposite corner of the slab, your arrows may clip through and hit the block behind it.
Wooden slabs can currently only be properly collected with a pickaxe instead of an axe. This may be caused because all 4 slabs use the same data value.
When walking with 50-100% of your body over a slab, whilst being at the high of another block, the walking sound effect for the slab type will play, rather than the one which you are actually on.
It is possible for multiple water currents to crash against each other and create an inescapable rip-tide. Not only will this rip tide hold you in one place, it will also throw you from a boat if you are sailing it.
Under certain circumstances, underwater players can breathe, and see through the water. An example is shown here.
Like lava, when water is touching the same corner as you it has a possibility of colliding with you, allowing you to float upwards.
Numerous strange objects will prevent the flow of water such as signs, sugar cane, doors, fences and half-blocks.
Water sometimes doesn't flow into newly generated areas.
If you access a workbench and press the jump key, sneak key or a movement key, your character will act as though that key is still being held even after exiting the workbench's interface. This can be fixed by pressing the same key after leaving the workbench's interface.
Mac OSX
On some Mac OS X Systems, the World Select screen will not appear at all, making the game unplayable on those Mac systems.
In other cases, the Mojang AB logo will appear green and the title screen and the game in dark areas will appear red.
In dark areas some sides of tile blocks will not render making a see through cave and grass and trees in daylight will appear purple, anything in darkness will also not render properly. The sound and music will also be weird. This has only been proved with non-Intel chip Mac.
on some Mac OS X systems, when the player is done and ( X'es out of the window ) the computer will take hours to close. The mouse will be able to move, but the windows and anything else will not be available until it closes. And when it does, the top bar on the screen will become black, and hard to see, so, either way, you will have to shut down, or keep the window open forever.
Survival Multiplayer (SMP)
General
If a player has respawned, he can place blocks on the block he is currently standing on. This will not decrease the block count in his inventory, effectively cloning blocks. This bug only occurs with non-opped players.
Full server world saves do not reliably save the entire world. This can be proven on a single person private server with whitelisting enabled when attempting to do a full server save via:
Disabling incremental level saving with 'save-off' on on Minecraft console.
Forcing a full save to disk with 'save-all' on on Minecraft console.
Archiving and saving the archived world with 'tar -xvzf save.tg world' on shell in secondary system console.
Turning back on incremental level saving by doing a 'save-on' on Minecraft console.
Enormous, cuboid areas (usually one or two chunks) of unfinished map open in random places. Caves, minerals, water, magma and mobs are visible when a Player peers into one of these voids. These areas cannot be walked on, causing a "[user] moved wrongly!" message to appear in the Server; however, players can ride minecarts through them with relative ease. If the void appears in the middle of water, Players can "float" over the void using a boat. Placing a torch next to one of these "void holes", dumping lava or water nearby, or disconnecting and reconnecting to the server will make the land inside of them reappear. These have become significantly less common since the 1.3 update.
When you sneak (in third person), your character's feet are "in" the ground.
Occasionally, the level.dat file is re-written, causing Minecraft to generate a new spawn. Also occurs in SSP.
If you ride a boat over a chunk of water which did not load properly ( ex. the water is really there, but you can't see it and can see through the whole world ), the boat disappears.
When a Boat gets damaged (by a player), it does not shake.
If you open and close a wooden door repetitively while jumping, you can catch yourself in the door and jump again. This can be used to reach places 1 block higher or to get on top of wooden doors overall.
The records duplicate if you eject the record before the song has finished. Only one record can be picked up however, the rest are client-side duplicates.
Engines consume coal but do not move under their own power, making them useless.
Empty/Storage Minecarts start to behave strangely when they are too far away from the Player. They disappear completely, disappear until Players disconnect and reconnect, or suddenly stop on tracks despite having sufficient momentum.
Minecarts load before terrain sometimes causing them to be invisible until they are interacted with. Large transit systems and door water boosters are examples of when the issue occurs. (log out/in to reproduce).
Shooting animations (Ghast fireballs/opening mouth and eyes, Skeleton arrows) are not always visible.
Ghasts' fireballs occasionally do not explode, only lighting a small area on fire.
Sometimes mobs freeze in animation and can not be hit. They disappear after about 2 minutes. They are client-sided, so no other players will see them.
Some users are reporting mobs will be invisible, but can still attack you. On update 11/24/2010 SMP health update post Notch explained that to see invisible mobs, players must set their difficulty to the server side difficulty or higher.
This does not always fix the problem; on occasion, mobs will fail to load client-side.
Sometimes when the character dies, monsters will stay loaded client-side and not be loaded on the server side.
Sometimes players can hit mobs multiple times before the server registers the hit. The hits will then all register at once and the mob will be subjected to several knockbacks at once, flying into the air.
When a mob dies, its corpse sometimes sticks in the red death animation and doesn't despawn.
When slimes divide in SMP they may create client-side duplicates.
The lower half of mobs can not be hit with a melee weapon when you are 1-2 blocks below them. They can, however, be hit from directly underneath.
TNT lit by one user cannot be seen by another, though its effects can.
Occasionally, a TNT block meant to drop will enter a repeating fall animation (but not actually fall) when lit. When the TNT finally explodes, it will explode at the position it was placed.
Occasionally, a TNT block can also explode twice, but this will not damage the environment twice.
If a lot of TNT is lit, some TNT may explode but leave behind an image of an exploding TNT block that is almost completely white, and will hover in mid-air. The ghost TNT will not disappear unless the player disconnects and reconnects. (This is a client-side TNT entity)
Trees that have grown recently, especially packed together in a tree farm, sometimes don't update the client with the leaf positions. This creates "invisible" leaves that the player can't walk through and makes navigating tree farms an annoyance.
Using bone meal to quick-grow trees will sometimes cause "floating" trees to grow with the sapling still at the base. Removing the sapling or using more bone meal can cause the tree to grow into an enormous bundle of leaves with no log base. These leaves will now respawn immediately after being harvested. The only way to remove these glitched leaf blocks is to burn each block individually (fire will not spread for some reason) OR build an umbrella above it, the shadow seems to instantly vanquish the leaves. - This glitch is vastly more common when quick-growing trees under another trees foliage. Again, disconnecting and reconnecting will reset these "ghost trees."
Planting a sapling and waiting a bit will sometimes yield tree trunks with weird distributions of leaves, and in some cases, no leaves at all. Trees can also grow but be invisible, making it impossible to traverse a tree farm after a while. Rejoining the server appears to make invisible trees visible again and fire will swiftly cause phantom foliage to be made manifest. You can also place a torch to make the phantom foliage appear.
Leaves from trees will overwrite some blocks, such as a nearby fence.
Placing a torch on Leaves does not make the 'pop' sound for the item being placed.
You may find yourself drowning despite having a full breath meter. This is caused by the client registering that the player has gotten air, but the server registers that the player is still underwater. This causes the non-synced breath meter.
