The picture had a two-week rehearsal period in which, during this time, writer Neil Simon customized the screenplay to tailor the lead stars' personalities. During the two-week rehearsal period, Simon observed the needs of his stars and was able to re-write portions of the script to better suit their individual personalities. "There is a terrific quality about Chevy (Chase)," says Simon, "He's the bad boy in class. You never know what he is going to do. I tried to capture that in the script and in each day's re-writes."
Marsha Mason and Burt Reynolds were touted as the leads in this movie according to this film's early publicity. These roles were eventually cast though with Goldie Hawn and Chevy Chase instead.
According to Turner Classic Movies, The Talk of the Town (1942) was a major inspiration for Neil Simon.
For Neil Simon, working with Goldie Hawn, was a delight. Simon said of Hawn that she was a "rare combination. She can be very funny and very sexy. She has a true appreciation of what's funny, and what's bleak in life" and "She has the two main ingredients for a film comedienne: she's funny and very sexy. Audiences respond on two levels to that. They are taken by it. She's terrific to work with."