The EN World kitten
Elves could be resurrected, they just couldn't be raised.Ugh, that one. That's right up there with elves can't be resurrected, except with a rod ... except less understandable.
Mine was hit points. There's a big section in the DMG saying how hit point loss represent a whole mess of things besides physical damage, and then the basic spell to recover hit points is named cure light wounds and is described as restoring "1 to 8 hit points of wound or other injury damage to the creature's body to be healed."1E was full of contradictions. The DM really had to make it up as you go.
My favorite was the Bard - The bard could be a half-elf or a human. To be a bard you first had to dual class in fighter and Thief, then you could take your third class in Bard ..... but half-elves were not allowed to dual class ..... so they could be Bards, but they could not earn the class prerequisites to be a Bard!