A German woman who was a Playboy centerfold was originally cast as Rebecca, but was let go after she had a drug overdose. Marianne Faithfull was subsequently cast in the lead.
Marianne Faithfull's gift motorcycle is a Harley Davidson Electra Glide; Alain Delon rides a 750cc Norton Atlas.
This was the first film to receive an 'X' rating from the MPAA in the United States.
The title character of the film, Rebecca, was inspired by a real-life 'girl on a motorcycle', the German racer Anke Eve Goldmann, a friend of the book's author, Andre Peyre Mandiargues. Goldmann designed her own one-piece leather riding suit in the early 1950s, and cut an amazing figure riding her BMWs in the 50s and '60s.
Billy Ivy, 1942-1969, was the stand-in motorcycle rider for the medium to long shots, presumably wearing a blond wig.