Visible crew/equipment: Near the end of the movie, before they turn into wolves, you can see the reflection of the crew in the window.
Other mistake: When Lawrence is looking at his wound in the mirror, it has slightly healed. Later, when Sir John visits Lawrence in the asylum, he shows the bite mark he got from the feral child to Lawrence. Since Sir John is also a werewolf, the bite mark should not be there.
Gwen Conliffe: It is said, there is no sin in killing a beast, only in killing a man. But where does one begin and the other end?
Trivia: Maybe more coincidence than trivia, but towards the end of the film, Gwen shoots and kills the Wolfman/Lawrence Talbot - in effect, beauty kills the beast. In Universal Studios' other major classic monster movie, King Kong, the beauty kills the big ape, albeit indirectly.
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Question: When John is telling Lawrence about the argument with Ben, John says that Ben would have taken Gwen away from him. Does this mean that John was secretly in love with Gwen?
Answer: Of course, probably not real love, but he wanted to possess her.