Lionel Atwill, who plays Professor Moriarty in the film, earlier played James Mortimer in The Hound of the Baskervilles.
A modern source lists Philip Van Zandt as Kurt and includes Henry Daniell in the cast as well. However, the role of Kurt is played by Harry Woods and neither Van Zandt nor Daniell appear in the film at all. The unidentified actor mistaken for Daniell plays a Scotland Yard detective slowly driving the police vehicle following the trail of paint, toward the climax of the film. First seen in 3/4 profile leaning out the car window, he does seem to resemble Daniell. However, when he speaks the accompanying line "they fade out again sir" to Dennis Hoey (Insp. Lestrade), and subsequent lines, he clearly has a rather heavy *Brooklyn* accent, and seen in other shots during the scene does not in any way resemble Daniell, and the momentary appearance to the contrary is clearly an optical illusion.
Although the main plot revolves around governments and wars that came to be only after Sir 'Arthur Conan Doyle''s death, the secret code from Doyle's short story "The Adventure of the Dancing Men", is incorporated as a subplot.
One of several titles in the Sherlock Holmes series whose original copyrights were apparently not renewed and have thereby fallen into public domain; as a result, seriously inferior copies are presently being offered by a number of VHS and DVD dealers who do not have access to original studio masters.
The fourth 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.
The lines that Holmes quotes at the end of the film are a condensed version of William Shakespeare's lines from Richard II. Richard II, 2.1, 40-51
The set used for Professor Moriarty's hide out was used as a pub/bar in Sherlock Holmes and the Voice of Terror.
This was the first of Universal's Sherlock Holmes series in which 'Dennis Hoey' appeared as Inspector Lestrade of Scotland Yard.
This was the second Sherlock Holmes feature to be produced at Universal. It was the first to be directed by Roy William Neill.