Revealing mistake: When Shrek and Donkey are sitting by the fire and looking at the stars, when Donkey asks Shrek about "our swamp" and Shrek says "We?" When Shrek blinks, his right eyeball is slicing through his upper lid. (00:46:30)
Revealing mistake: When Donkey first meets Shrek, when Shrek confronts the knights, not all the shadows fall the same way. Shrek's shadow is cast forward onto the leader knight, whereas the knights' shadows are off to their left.
Revealing mistake: When Donkey and Shrek are walking through the garden area, they pass some sheaves of wheat (presumably.) If you look carefully, you will notice that the wheat stalks were cut, not pulled up, but what were they cut from? There is only bare earth. (00:27:45)
Revealing mistake: In the escape scene, before the bridge breaks, Shrek's left arm passes through the ropes.
Chosen answer: The Andorians on Star Trek.
Grumpy Scot