(at around 1h 16 mins) To get the proper look of derision from Linda Darnell in the scene where she stares at a photo of Addie, director Joseph L. Mankiewicz used a picture of Otto Preminger, the director who had given Darnell such a hard time on the set of Forever Amber (1947).
(at around 47 mins) Joseph L. Mankiewicz had a real battle with the American censors at the time who would not permit him to use words like "laxative" and "toilet" in his script. He got his revenge with a famous double-entendre laden exchange which used words like "penetration" and "saturation".
At one point the film was called "A Letter to Four Wives". Upon submitting the adapted screenplay to 20th Century-Fox chief Darryl F. Zanuck, Joseph L. Mankiewicz mentioned that he found it too long and asked how he felt the movie could be shortened. "Take out one of the wives," Zanuck replied. Originally, the movie would have featured Anne Baxter as the fourth wife. Zanuck didn't feel Baxter's segment was as strong as the other three, so that one was cut.
This film was based on John Klempner's novel, "A Letter to Five Wives." Two wives were lost in the transition to the screen.