During filming of an action scene, a bullet ricocheted and struck director Robert F. Hill in the head. The injuries he incurred caused him to retire from active directing three years later.
Ralph Byrd gets top billing in this movie, but he does not play Blake of Scotland Yard. Blake is played by Herbert Rawlinson.
The Death Ray Machine is the same as the Earthquake Detector in Império Submarino (1936) Chapter: 1. This electrical gadget was previously used as part of Prof. Carl Van Dorn's lab equipment in A Sombra Misteriosa (1934). Ken Strickfaden created this piece of lab equipment for the original Frankenstein (1931) movie and it appeared in A Noiva de Frankenstein (1935). The actual name given it by Ken Strickfaden was "The Cosmic Ray Diffuser." It has been use a many movies.
Chapter: 14 is a budget-saving recap episode where sequences from previous chapters are shown for most of the running time.