When Kurt tries to seduce Lisabeth in her room, she is not under covers, but when she leaves, swearing he'll have her, she is.
When Kurt hears something down in the crypt and leans on the door, his face is different and he is looking downwards in the shot that follows immediately.
Mary has a noticeably different look on her face when Kurt starts walking away from dinner than in the shot before, all part of the same scene.
Obvious doll is used to replace the actress at the start of the movie in the burning scene.
In a few scenes, the film tries to simulate the darkness, so when the characters blow out the candles it gets darker. However, the lightning in these scenes is not consistent and it's obvious that studio lights are present, providing light to the set. For example, in one scene in particular a woman carries a candle and studio light follows her, simulating the candlelight that would be a lot weaker.
When Lisabeth notices the wheel that opens the secret passage, the wheel starts turning on its own just before the shot of it ends.
In one scene a mouse moves a skeleton making it look like its moving on its own. A mouse could never move the whole skeleton like shown.
In one scene a man and a woman get trapped in the crypt because they cannot reach the key that is supposedly out of their reach, but it's obvious they could reach it with a little bit more effort.