Revealing mistake: When Dan Holland, Kate, V.I.N.CENT and old Bob battle Reinhard's robot sentries on the catwalk, part of the bridge the sentries stand on is critically damaged and collapses. In that shot, the sentries are model figurines.
Revealing mistake: When Sweetums scares the girls out of the tent, watch the first girl that runs out screaming. If you look at her face closely, you can see that she is smiling.
Revealing mistake: Dave is racing with the Italians, and the Italian puts his pump in Dave's spokes. In the middle of the bike falling over, you see a horizontal beige object with duct tape on it for a couple of frames, where you should see Dave.
Revealing mistake: When the ghost (Bugs Bunny) tells Scrooge that he is going to take him to "the man in the red suit", the ghost puts his arms up but the shadow does not.
Revealing mistake: Just before the battle between King Arthur's men and Sir Mordred's men, Trimble Tom escapes from Sir Mordred's encampment in a rocket-powered chair. As he approaches King Arthur's Castle you can see the wires supporting the chair. (01:15:45)
Revealing mistake: In the closeups the boy is holding a large leaf of seaweed to offer the stallion. But in the long shots at the waterfront he extends an empty hand with no seaweed visible.