Trivia / The Sign of Four: Sherlock Holmes' Greatest Case

• The Other Darrin:
  • Ian Hunter plays Dr. Watson, replacing Ian Fleming from the previous entries in the Wontner-Holmes series, as it was felt that a younger actor would be more believable for the romance scenes with Mary Morstan. Fleming would return for the next film The Triumph of Sherlock Holmes.
  • Clare Greet also temporarily replaces Minnie Rayner as Mrs. Hudson.