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.
Continuity mistake: When the ghost (Bugs Bunny) appears to Scrooge, he has his arms up and his eyes wide. But we see a close up of the ghost in the next shot, his arms are outward and his eyes are angry.