Revealing mistake: In the scene where Lawrence Talbot and Sir John Talbot are talking, Sir John Talbot is blowing out candles, but they are filament lamps, because the third candle lamp actually goes out before he blows on it.
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.
Dr. Hoenneger: Now, we are all aware that Mr. Talbot has suffered quite traumatic personal experiences. He witnessed his mother's self mutilations. His young mind, unable to accept it, created a fantastical truth, that his father is to blame. That his father is literally a monster. [Turns to Lawrence.] But, your father is not a werewolf. You were not bitten by a werewolf. You will not become a werewolf, any more than I will sprout wings and fly out of that window.
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.