Despite writer / director Paul Annett's objections, producer Milton Subotsky (who hated this movie) insisted on the werewolf break gimmick where the viewer was invited to guess who the werewolf is.
Due to the small budget, the werewolf was played by a German Shepherd.
Hammer Films and Amicus Pictures produced numerous horror films involving ghosts, vampires and devils over a period of 20 years. Both of them, however, only produced one werewolf movie each. This was Amicus' effort. Hammer's was The Curse of the Werewolf (1961), an early starring vehicle for Oliver Reed.
Robert Quarry was originally slated to play the lead, but at the last minute the producers went with Calvin Lockhart instead, in order to capitalize on the then-hot blaxploitation craze.
One of the unforeseen challenges of casting a black actor was that it caused problems lighting the numerous day-for-night sequences, a cost-cutting method where nighttime scenes were shot in the day with the addition of special filters to make it appear that it was filmed at night.