Minecraft wiki entry for Development_versions, associated text: MC-3090 – Unable to play game unless LWJGL is manually replaced.
MC-4253 – Endermen are rendered hostile if they take environmental damage.
MC-5674 – Client can control if they take damage and abuse this / ALT or F10 freezes client in windowed mode.
MC-11229 – Using the anvil for free.
MC-12017 – Can get permanently stuck in a minecart in a nether portal.
MC-12369 – Minecraft crashing on 1.5.1 prerelease server.