Continuity mistake: When Don Knotts is in the old Simmons mansion, he falls down a chute of some kind. If you watch closely you will see the stunt person looks nothing like Don Knotts. It is a younger man with very straight hair.
Continuity mistake: When Peter O'Toole is locked in the closet at the museum, he puts a rope through the keyhole and uses a hook to pull it under the door. In the first shot, from outside the closet, the end of the rope is to the right. In the next shot, from inside the closet, the end of the rope slides under the door to the left. (01:22:30)
Continuity mistake: As George says "That you people are rearranging my genes so that everyone will be like everyone else" he puts his left arm around Nick. His hand, though is on the back of the sofa. Instantly in the next shot, however his left hand is now on Nick's left shoulder.
Continuity mistake: Under the shower, Alva holds the envelope Owen gave her in two different ways that keep switching, depending on which take they used in editing. (01:19:05)
Continuity mistake: When Alfie helps a woman out with a doctor, it's raining, but when Alfie goes outside the rain has stopped and there's no water on the ground.