Shirley MacLaine and Robert Mitchum began a love affair that lasted for years during the shooting of this film.

Based on the Broadway play, which starred Anne Bancroft and Henry Fonda.

Elizabeth Taylor and Paul Newman were both set to do this film but when Taylor became ill during the early filming of Cleopatra (1963), Newman was able to do The Hustler (1961) instead.

Giving a drunken promotional interview for Ryan's Daughter (1970) to the young Roger Ebert in 1969, Robert Mitchum vented his low opinion of director Robert Wise: "Bobby even times a kiss with a stopwatch. He marks out the floor at seven o'clock in the morning, before anybody gets there. Lays it all out with a tape measure. True. It's very difficult to work that way. I worked with him and Shirley MacLaine and Shirley said, 'Why doesn't he go home? He's just in the way...' "

The original Broadway production of "Two for the Seesaw" by William Gibson opened at the Booth Theater in New York on January 16, 1958, ran for 750 performances and was nominated for the 1958 Tony Award for the Best Play.

The producers paid $350,000 for the film rights to the Broadway play. According to an article in the 18 May 1962 edition of the New York Times, the Mirisch Co. bought the rights at the request of Elizabeth Taylor, who wanted to play the lead. But because of her long-term commitment to Cleopatra (1963), she was unavailable.

Glenn Ford, James Garner, and Paul Newman were considered for the male lead in this film.