Snapshot 13w07a, Snapshot 13w09a, Snapshot 13w09b, Snapshot 13w09c, Snapshot 13w10a, Snapshot 13w10b, Minecraft 1.5, Snapshot 13w11a, Minecraft 1.5.1, Snapshot 13w16a, Snapshot 13w16b, Minecraft 1.5.2, Snapshot 13w17a, Minecraft 1.6.2
If a player saves and quits to the main menu whilst the Ender Dragon is doing its dying animation, reloading the world will cause the dragon to appear alive and spin in circles.
Steps to Reproduce:
1. Make a new Creative world.
2. Construct an End Portal and enter it.
3. Using an Anvil, enchant a bow with Power V.
4. Destroy the Ender Crystals and attack the Ender Dragon.
5. After you successfully kill the dragon press escape and quit to the main menu.
6. Reload the world and observe how the death animation is glitched.