For the shot where Tom rides through the brick wall on his motorcycle, a wall was built of Styrofoam and painted to look like brick. When the stunt was first performed with the fake wall, the motorcycle shot through the structure but the rider was knocked off the cycle.
The film was almost universally blasted by critics upon its release. One reviewer for the London Times wrote that the film was only fit to be shown at an "SS reunion party."
During a BBC interview, Nicky Henson said that he has always thought the film was terrible and only decided to be in it because he thought no one would ever see it. He was surprised to find himself being interviewed about it 40 years later.
This is not the first Don Sharp film to feature frogs in cemeteries, pacts with the devil, mysterious suicides, and the living dead. These are also motifs in his earlier film Witchcraft (1964).