Goofs

Margaret uses putty or clay to take an impression of the keyhole of the lock on the laboratory door. This would not work, as the lock is a Yale type of barrel lock with internal levers. Soft putty would only gum up the internal workings, and when it was completely dry it would be impossible to remove intact.

The barrel lock on the laboratory door does not have a bolt. This can be seen most clearly when the edge of the door is visible when Margaret opens the door with her copy of the key.

During one of the laboratory scenes in the film, a boom mic's shadow is clearly visible.