In interviews both Bill Murray and Richard Dreyfuss admitted that they did not get along during filming.
Dr. Leo Marvin is a psychiatrist whose children's names are "Sigmund" and "Anna". They are named respectively after the famous psychiatrist and psychoanalyst Sigmund Freud and his daughter, child psychologist Anna Freud.
Robin Williams was the first choice for the role of Bob Wiley, as he had been nominated for an Oscar for his performance in screenwriter Tom Schulman's Dead Poets Society (1989), also distributed by Touchstone Pictures. However, at the time filming was to begin, Williams had just finished filming The Fisher King (1991) and was forced to turn down the role. Williams and Charlie Korsmo, who plays Richard Dreyfuss's son in this movie, would go on to star in Steven Spielberg's Hook (1991) the same year.
When Fay Marvin was tucking in Bob and her son Sigmund on the night of the Bob sleepover, she holds the sheets up to allow Bob to climb into his bed. Bill Murray improvises in the scene and crawls under the sheets head first, cracking up Julie Hagerty.