Lana Turner was offered to play the of Deidre but she balked at a scene where she kisses her female lover on the lips. The part was offered to Alexis Smith and she accepted.
The movie was made and released in 1975 after source novelist Jacqueline Susann had passed away in 1974.
The title of the Jacqueline Susann novel and film "Once Is Not Enough" derives from a conversation Susann had with her old friend, comedian Joe E. Lewis, on his deathbed. Trying to perk up his spirits, she supposedly said, "Come on, Joe. Didn't you always say 'you only go around once, but if you play your cards right, once is enough'? Lewis responded, "I was wrong, Jackie. Once is not enough."
The relationship between and Deidre Milford Granger (Alexis Smith) and Karla (Melina Mercouri) was allegedly based on the real-life relationship between heiress Barbara Hutton and film star Greta Garbo respectively.
Brenda Vaccaro was the long term girlfriend of Kirk Douglas's son, Michael Douglas, at the time.