Revealing mistake: When the Pterodactyl is flying around with the egg, its shadow isn't cast as she flies over the trees.
Revealing mistake: In the scene where Rocky and Bullwinkle are walking through the university with Kenan and Kel (right before they come across the anti-moose protest), Kel's right arm passes through Rocky's left several times.
Revealing mistake: When Spencer is walking over to the computer, he clips through the rocking horse. (00:01:39)