Continuity mistake: When Mary reads the measuring tape after measuring herself the message reads up and down (as shown to the audience), but then the camera shows Mary reading it side to side.
Continuity mistake: In the part of the crazy car ride when the other vehicles start going in reverse instead of colliding head-on with Harold, he has his arm across the face in the front view, but in the reverse shot just the hand is raised. (01:08:40)