Continuity mistake: Harry stands on top of a building with a girl folding paper planes. The plane they fold is folded with a blunt front. He throws it off the building and then the plane flies, all of a sudden the nose is sharp, this is visible.
Factual error: When Marion picks up the phone to call to score a hit, the number she should dial is 934 8777. However, listen to the pitches of the keys she dials. The pattern should sound like: EECDCCC. The pattern she dials is: DCDEDDD. She is clearly not dialing 934 8777.