Continuity mistake: In the scene where Gustav and Count Orlock are discussing the real estate contract, the locket that falls out of the bag first shows a photo of Greta, but in the next shot, it is a painting that looks completely different.
Factual error: After a new camera man is hired, Wagner, the camera man starts showing off to his fellow crew members that he invented "slow motion". In the next scene he demonstrates this by spinning the handle of the camera slowly. In fact this is not right, when the movie is projected the movie will be speeded up instead of slowed down.
F.W. Murnau: I will not allow you to destroy my picture.
Max Schreck: This is hardly your picture any longer.