The film was inspired by writer and co-star Brian Doyle-Murray's memories of working as a caddie at Indian Hill Club in Winnetka, Illinois. His brothers Bill and John Murray (production assistant and a caddy extra) and director Harold Ramis also had worked as caddies when they were teenagers. Many of the characters in the film were based on characters they had encountered through their various experiences at the club, including a young woman upon whom the character of Maggie is based and the Haverkamps, a doddering old couple, John and Ilma, longtime members of the club, who can barely hit the ball out of their shadows. The scene involving a Baby Ruth candy bar being thrown into the swimming pool was based on a real-life incident at Doyle-Murray's high school. The scene in which Al Czervik hits Judge Smails in the genitals with a struck golf ball happened to Ramis on what he said was the second of his two rounds of golf, on a nine-hole public course.