Revealing mistake: At the end of the film, when Peabody drops off Sherman for school and has just told him that he loves him, there's an animation error occurring in the background in the form of a car going from full speed to instantly being completely frozen. (01:21:00)
Revealing mistake: In the POV shot from Thomas, capturing Bill and Ben puffing away from the water tower, Thomas seems to be off-centered from the tracks, making it seem like he is derailed.