American International Pictures insisted on playing up the horror-occult themes of the film when marketing it. As part of this, the film's original title was changed to the more ominous "Burn, Witch, Burn" - a line that Margaret Johnston speaks in the film. Also, the voice-over opening where a spell is cast upon the audience was added for setting the tone.
Star Peter Wyngarde initially found the script for "Burn, Witch, Burn" (titled "Night of the Eagle" at the time) to be "rubbish" and decided to pass on the film. Later when Wyngarde saw a luxury car that he desperately wanted to own he went back and took the role of Norman Taylor: asking to be paid exactly the amount for the cost of the car.
The original script contained much more occult and voodoo material. However, this was cut down as director Sidney Hayers felt the relationship of the Taylors needed to be the focus of the film.
Peter Wyngarde attended the premiere of the film with fellow British actor Alan Bates. Much to his disdain, he and Bates were the only people in the audience. Years later after the film received an American release, Wyngarde was pleased to learn that "Burn, Witch, Burn" played in Times Square for several years and found a bigger audience.
The stone eagle is shown in the foreground or background of every scene at the university.