- Makeup artist Jack P. Pierce estimated it took four hours to transform Boris Karloff into the monster.
- This film marks the final time Karloff would play the "Monster". The next Frankenstein film Karloff appeared in, House of Frankenstein (1944), he plays Dr. Gustav Niemann. Thus, he played the "Monster" three times in his career.
- The film was originally to be shot in color, but the decision was made at the last minute to stay in black and white. Color test footage and photographs of Karloff as The Monster reveal the Monster was to have had a green face. A rare color gag movie of Karloff in Monster make-up pretending to strangle make-up artist Jack Pierce can be seen on the CD-ROM Interactive History of Frankenstein, The (1995) (VG).
- At 99 minutes, this was the longest film in the classic Universal horror series. Most of the films had running times of less than 80 minutes.
- 'Peter Lorre' reportedly turned down the role of Wolf von Frankenstein.
- Boris Karloff became the father for the first time while filming this movie. When he was told that the baby had been born, he immediately went to the hospital to see his wife and child while still in costume. When he arrived, in full Monster makeup and clothing, he created a panic throughout the hospital.
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