When listing what has happened to him since meeting Sue Ann on Monday, Dennis says, "Wednesday, I was unfaithful", a remark he immediately dismisses as a fantasy by saying "that was in another country"--a reference to famous lines in Christopher Marlowe's play "The Jew Of Malta" ("But that was in another country/And besides, the wench is dead"). However, Lorenzo Semple Jr.'s screenplay did originally contain a sequence in which Dennis is seduced by his much-older landlady Mrs. Bronson; it was omitted from the film.

Tuesday Weld hated working with director Noel Black and told film critic Rex Reed that she thought she gave her "worst performance" in the film. However, she got rave reviews for her work, and, in later years, following her retirement, many critics have called it her finest performance.

The movie that Dennis and Sue Ann go to see in their local theater is Roger Corman's The St. Valentine's Day Massacre (1967), released by Twentieth Century Fox a year before this film was released. The same scene that is glimpsed here also turns up as stock footage in a later film, Capone (1975), which Corman produced.

At the end of the film, the owner of the stand throws garbage into the river. The plant at which Tony Perkins works discharges its effluent into the river and pollutes it. In 1968, all of this was legal. The disposal of any waste into public property is called "negative externalities". The owner of the stand and the manager of the factory don't WANT to pollute public property but they had no incentive to do otherwise until around 1970, when President Nixon created the EPA and signed laws into effect, called a Pigouvian tax, that caused polluters to share the social cost of the pollution.

Sue Ann's car is a 1968 Sunbeam Alpine Series V.