When Nichole (Noëlle Adam) had to slap Jennifer (Gillian Hills) in a scene, Jennifer kept anticipating the slap and turning her head prematurely, so on one final attempt Nichole went for it and caught her with a real hard slap not giving her a chance to pre-empt the slap.
The soundtrack album was the U.K.'s first long-playing record devoted to a single movie score.
Gillian Hills was fourteen-years-old when making the movie. Adam Faith eighteen, and Oliver Reed twenty.
Gillian Hills said Adam Faith was so normal and natural and under-playing everything, while she was overdoing everything "like a fourteen-year-old Shelley Winters".
When making this movie, Gillian Hills was fourteen, the same age as Sue Lyon around the same time in Stanley Kubrick's Lolita (1962). A decade later, Hills would play one of Alex's two conquests, Alex portrayed by Malcolm McDowell, in Kubrick's A Clockwork Orange (1971) (the famous sped-up sex scene).