The oldest movie ever to be featured on Mystery Science Theater 3000 (1988)., and one of the very few from the 1940s. The Mad Monster (1942) is a close second, having been released one week after this film.
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.
In a scene where Bela Lugosi watches over a sleeping Luana Walters, the music heard comes from the 1933 Majestic feature The Vampire Bat (1933).