Minecraft wiki entry for Development_versions, associated text: When placing the Anvil in mid-air in a certain orientation the entity will be sideways until it lands.
Breaking the block under any Anvil resets it to a regular Anvil.
When using the /kill command an error appears, when holding a block it gives the normal message but you don't die.
When in a multiplayer server and trying to rename an item, if entire name is erased the client will crash.
Using fortune ≥ IV (normally impossible to obtain) on gravel no longer causes a game crash.