Shot in six days.
George Zucco's estate from an earlier PRC film, The Mad Monster (1942), serves as the crypt for the evil twin.
Indicative of just how low this Poverty Row quickie's budget was, every time Zucco's evil twin Elwyn "disappears before our eyes," the effect is achieved by doing a simple dissolve from a shot of Zucco standing in front of a door or window to a similar shot of the same set standing empty.. At the time this was made, this "special effect" would've cost about $25 a pop, and was therefore limited to only a handful of uses.
Dwight Frye, who plays Zolarr in this film, has the distinction of being one of 2 actors to appear in the original Frankenstein (1931) and the original Dracula (1931), both released in 1931; Edward Van Sloan was the other. Frye later played roles in several of Universal's horror sequels, including Bride of Frankenstein (1935) and The Ghost of Frankenstein (1942).