Boris Karloff, who was actually an Englishman (true name: William Henry Pratt), plays a Hungarian scientist. Bela Lugosi, who was actually a Hungarian plays a Frenchman.
Frank Reicher's character is incorrectly listed in the credits as 'Professor Mendelssohn.'
Part of the original SHOCK THEATER package of 52 Universal titles released to television in 1957, followed a year later with SON OF SHOCK, which added 21 more features.
Shooting lasted from Sept. 17-Oct. 25, 1935, release was held up due to the extensive special effects done by John P. Fulton. Issued January 10, 1936.
The church in which Frank Lawton and Frances Drake get married, though called the "Church of the Six Saints" in the film, is actually the set of Notre-Dame Cathedral recycled from the 1923 Universal production "The Hunchback of Notre-Dame," starring Lon Chaney, Sr.
The scene of Boris Karloff being lowered into the pit containing the Radium X meteor was reused in a 1939 Universal serial, "The Phantom Creeps," starring Bela Lugosi. Karloff essentially "doubled" for Lugosi in the sequence since in "The Phantom Creeps" it was Lugosi who was lowered into the pit.