Filmed 13 March - 1 April, 1942, the fourth of Bela Lugosi's nine Monogram features.
The failure of the original copyright holder to renew the film's copyright resulted in it falling into public domain, meaning that virtually anyone could duplicate and sell a VHS/DVD copy of the film. Therefore, many of the versions of this film available on the market are either severely (and usually badly) edited and/or of extremely poor quality, having been duped from second- or third-generation (or more) copies of the film.
The earliest documented telecast of this film took place in New York City Wednesday 7 June 1950 on the DuMont Television Network's WABD (Channel 5).
The music Dr. Lorenz plays on the organ in two separate scenes is "Ave Maria."
Dr. Foster (Tristram Coffin) drives a 1938 La Salle.
One of the movies "riffed" on Mystery Science Theater 3000.