This low-budget thriller, boosted by Bela Lugosi, was one of the biggest successes for the poverty row Producers Releasing Corporation (PRC). After the war, the studio tried to recapture this success by producing an in-name-only sequel, Devil Bat's Daughter (1946), and a virtual shot-by-shot remake, Le trésor des Aztèques (1946).
Because it was produced by the "poverty row" studio PRC, which failed to renew its copyright, the film is now a public domain title. This explains why it is frequently run on late-night TV, and is available on home video from multiple distributors, often of very poor quality.
Arthur Q. Bryan's role as editor Joe McGinty provided him with what is now his most famous credited on-screen role. If his voice sounds familiar, it is because he was the original voice of Elmer Fudd for Warner Bros.
There's quite an age difference between Dave O'Brien and Donald Kerr (reporter Johnny Layton and sidekick/photographer "One-Shot" Maguire). O'Brien was just 28 and Kerr was 49, although he sure doesn't look that old! Neither man was ever a big star although they always had plenty of work playing bit parts--and in Kerr's case, nearly always uncredited. Example: Kerr was in 29 movies in 1940 alone, all but 2 or 3 in uncredited bit parts. O'Brien is better known for his role in the whacky Stupéfiants (1938) (aka Reefer Madness) but he did a nice job in the much more serious 1945 feature about a modest war hero The Man Who Walked Alone (1945). And Kerr is better known as silly Happy Hapgood, reporter, who accidentally accompanies Flash Gordon to Mars in Les nouvelles aventures de Flash Gordon (1938).
This was the first, and most successful, horror film from Producers Releasing Corporation (PRC) after it was formed from the failed Producers Distrubuting Corporation (PDC). Filming began October 28 1940.