This was the first film in the United States to receive an X rating (in its original release). It opened in New York City on December 15, 1968.
A clip of this movie is on "The 50 Worst Movies Ever Made" DVD Region 1 NTSC.
Although this is actually Brian De Palma's second film, it was released before his first, The Wedding Party (1969).
Brian De Palma and his co-writer Charles Hirsch admitted that, in writing this film, they were greatly under the influence of Jean-Luc Godard's film, Masculin Féminin (1966).