Lionel Atwill was originally cast as Prof. Moriarty, but was replaced before shooting by George Zucco.
Alan Marshal, George Zucco, and Mary Gordon (uncredited) also appear in the 1936 movie, After The Thin Man.
Although William Gillette's name appears in the credits, this film bears little or no resemblance to his 1899 play "Sherlock Holmes".
The movie's line "Elementary, my dear Watson." was voted as the #65 movie quote by the American Film Institute (out of 100).
The second of fourteen films based on Arthur Conan Doyle's fictional consulting detective Sherlock Holmes starring Basil Rathbone as Sherlock Holmes and Nigel Bruce as Doctor Watson.