During its 1970 run as an X-rated feature-length film (really, a series of unrelated 3D shorts strung together with marginal connecting footage), posters and advertising claimed it was based on a best-selling book, which did not exist.
One of the most profitable films ever made, with a shooting budget of just over $100,000 (approximately $531,000 in 2005 dollars) and a worldwide gross of $25 million to $30 million.
Chris J. Condon, founder of Century Precision Optics, and director Allan Silliphant, developed a single-camera 3-D system that was simple and economical to use. In the 1950s, 3-D films had been shot with two cameras, and showing a 3-D film in a theater required two projectors, which often went out of sync. The new single-camera system put the two images side-by-side in a normal 35mm film frame, allowing use of a very portable camera. Condon's camera and technology, manufactured by Stereovision International Co., were eventually used to shoot many movies like Les Dents de la mer 3 (1983) during the 1980s 3D boom.
In the scene that features a band playing, one of the musicians is a then-unknown Paul Shortino, later in such bands as Rough Cutt and Quiet Riot.
Shot with a minimal crew. Shooting began with a general story outline instead of a full script. Typically, scenes weren't finalized until the camera was ready to roll.