Although the publicity for this movie made much of the fact that the three greatest horror stars of the day, Vincent Price, Sir Christopher Lee, and Peter Cushing, were all in it, the three actors have, in fact, only small roles in this movie, despite star billing. Cushing's role is confined to one scene, without the other two, the Price and Lee characters have a very brief scene together only at the end of the movie, and the combined footage for all three actors only comes to about one-fifth of the total running time.
Peter Saxon was originally a pen name of W. Howard Baker, but it came to be used by several writers working the same circuit, including Martin Thomas and Stephen Frances. The original novel was probably a "round robin", a collaborative effort between these three men.
Parts of the Keith (Michael Gothard) versus Police car chase were filmed not on a public highway, but using the Alpine Circuit at Millbrook test track, often featured in motoring magazines and programs. It would be used again for the car pursued by motorcycle sequence in segment four, "Wish You Were Here", in Tales from the Crypt (1972).