Revealing mistake: You can see the stick making the finger move when it's in the box. (00:38:20)
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 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.