Completed in violation of union rules limiting actors to 8-hour work days.
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.
Production wrapped late in the evening of March 15, 1941. Thanks to journeyman editor Otto Ludwig cutting the picture during production, with scoring swiped from earlier Universal pictures (including The Invisible Man Returns), allowed the picture to be released just 13 days later.
The Carfax Abbey stone staircase seen was originally used in Dracula. Many of the remaining sets were recycled from Tower of London.
The production was plagued by poor weather. In order to meet the tight 12-day production schedule, the cast and crew worked until midnight on several occasions. Star Dick Foran came down with a severe cold in the final days of shooting and missed a day's work. Consequently, his final scene was dropped.
Universal released this film only 25 days after shooting began on March 3, 1941, finishing on the 15th.
Universal, unlike most major studios did not own a theater chain, and produced this low budget B-programmer as a pre-packaged bill, along with Man Made Monster.
When the Professor is listening to a scary story on the radio the narrator is Vincent Price