Filmed in Eastman Color, but re-titled and released in USA in black-and-white.
John Ford was allowed to visit the Scotland Yard building during the shooting of the movie. The policemen asked him not to show the cups and saucers which were on officers's desks. And Ford finally filmed policemen's desks with cups and saucers on them.
Ronald Howard and Howard Marion-Crawford played Sherlock Holmes and Dr. Watson, respectively, in the mid-50's TV series Sherlock Holmes (1954).