The pie fight scene lasts four minutes and was shot in five days. It is the longest pie fight sequence in movie history. At first, the cast had fun filming the pie fight scene, but eventually the process grew wearisome and dangerous. Natalie Wood choked briefly on a pie which hit her open mouth. Jack Lemmon got knocked out a few times: "a pie hitting you in the face feels like a ton of cement". At the end of shooting the fight, when Blake Edwards called "Cut!" he was barraged with several hundred pies that members of the cast had hidden, waiting for that moment.
This film was the inspiration for the Saturday morning cartoon show Wacky Races (1968): Dick Dastardly and his sidekick Muttley were based on Professor Fate and Max, Penelope Pitstop was based on Maggie DuBois and Peter Perfect was based on Leslie.
Chris Lemmon, son of actor Jack Lemmon (Professor Fate), said in an interview on KMOX-Radio in St. Louis that he considers Lemmon's role in this film to be his father's finest. Jack Lemmon himself has said he got more mail about Fate than about any other character he played.
Jack L. Warner asked Tony Curtis if he would give a percentage of his film royalties to Natalie Wood as an enticement, but Curtis refused. He said, "I couldn't give her anything to make her want to do the movie." Curtis and Wood had worked on two films previously, and had developed an acrimonious relationship.
About 4,000 real pies were used in the pie fight scene, and the cast ate many of them during filming. However, during a weekend break in filming, the pies spoiled. The stink was so bad that the building required a thorough cleaning and large fans to blow out the sour air.