Ace the Wonder Dog gets billing on screen, as "By Himself."
Earned a B from the Legion of Decency due to "excessive gruesomeness."
In this film J. Carrol Naish's character Dr. Igor Markoff is compared to Dr. Frankenstein. Mr. Naish would later play Dr. Frankenstein in his very last film role, Dracula vs. Frankenstein.
Lowly PRC hadn't released a horror picture in nearly 17 months, having spent most of 1943 substantially expanding their once-laughable capabilities by purchasing the bankrupt Chadwick Studio (a poverty row operation that specialized in renting stages and production equipment to low-budget producers along Gower) for $305,000. While critics - what few that would review a PRC release - complained about the film's lack of action, production values were noted to be somewhat higher than earlier releases.
Originally titled: "The Devil's Apprentice."
Throughout the film, Dr. Igor Markoff and Steve make several references to Frankenstein. Later that same year, Glenn Strange (Steve) would go on to play Frankenstein's Monster for the first time in House of Frankenstein.