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.
Other mistake: When our heroes are on the conveyor belt in the rock-processing plant, none of the rocks are larger than two feet in size - especially having gone past a set of spinning saw blades - and yet they get sprayed by two steam nozzles, the highest of which is about six feet in the air, and the lowest is about four feet in the air. Clearly neither of these nozzles would have any practical use. (01:21:10)
Other mistake: An old woman in a dress shop peeps out to see all the cameras in front of her store before the Beatles run by on their way back to the studio. (01:13:40)
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)
Other mistake: When Col. Bat Guano shoots the Coke machine and it squirts him in the face, he's holding his head too high. You can see that he first gets the spray on the chin and then he ducks down to take it full in the face. (01:09:50)