House of Dracula (1945)

Revealing mistake: In the cave scene, when Dr. Edelman and Talbot come upon Frankenstein's monster in the mud, there is a skeleton lying beside the monster, which Dr. Edelman identifies as probably Dr. Niemann. The prop is an obvious lab skeleton, as you can very clearly see the circumferential line around the skull cap. Also, if you look closely in several shots, you can make out the hook at the top of the skull where it would hang from a lab stand. (00:24:35)

Dr. Edelman: Now, Mr. Talbot... You broke your promise to me, didn't you? Told the police. I don't like people who break their promises, Mr. Talbot.