In summer 1965, Jack Lemmon’s production company, Jalem Productions, Inc., acquired Hal Dresner’s screen story, The April Fools, as a starring vehicle for Lemmon, according to a 10 Aug 1965 DV news item. The following year, a 14 Mar 1966 DV brief announced that Universal Pictures had a film in development also titled The April Fools, conceived by Steve Previn; however, the 5 Oct 1966 DV reported that the Jalem project had registered the title first, forcing Universal to rename their film.
       The 30 Dec 1967 LAT stated that The April Fools would be the first in a four-picture deal recently negotiated between Jalem and CBS Theatrical Films. Twelve weeks of principal photography were slated to begin on 1 Apr 1968, with Stuart Rosenberg directing, the 9 Jan 1968 DV reported. Jane Fonda was approached to co-star with Lemmon, but the actress had to decline due to her pregnancy, according to the 7 Mar 1968 DV. Shirley MacLaine, who had acted opposite Lemmon in The Apartment (1960, see entry) and Irma La Douce (1963, see entry), was then offered the role, but an item in the 4 Jun 1968 DV stated that MacLaine would be unavailable due to her shooting schedule on Sweet Charity (1969, see entry). Catherine Deneuve’s casting in the role of “Catherine Gunther” was confirmed in the 25 Jun 1968 DV, which indicated that The April Fools would mark her American motion picture debut.
       Due to his growing concern over civil rights issues, Jack Lemmon pledged half his salary from the film to Dr. Martin Luther King, Jr.’s Christian Leadership Conference. According to an item in the 12 Aug 1968 LAT, the promised donation would amount to somewhere between $350,000 and $500,000.
       Filming began in New York City on 22 Jul 1968, as announced in a 26 Jul 1968 DV production chart. An article in the 18 Aug 1968 NYT indicated that airport scenes were shot at the TWA Flight Center at John F. Kennedy International Airport in Queens, NY. While on the East Coast, filmmakers also shot in Connecticut, as stated in the 12 Aug 1968 DV. Over the weekend of 10-11 Aug 1968, the production relocated to Los Angeles, CA, where some filming was set to take place at the CBS Studio Center in Studio City, CA. The Los Angeles Memorial Sports Arena also served as a location, the 19 Sep 1968 LAT indicated. The completion of filming was announced in the 23 Oct 1968 Var.
       Set decorations entailed “a lot of art,” as stated in a 29 Jul 1968 LAT item. Works provided by art dealer Felix Landau included a sculpture by Frank Gallo and a painting of a nude by James Gill. Lemmon’s wardrobe consisted of ten identical suits, according to the 5 Dec 1968 LAT, which noted that his character does not change in the thirty-six hours depicted onscreen.
       As stated in the 16 Apr 1969 Var, title footage was supplied by Pablo Ferro Films.
       Burt Bacharach, who co-wrote the theme song, “The April Fools,” with Hal David, was originally set to score the film, according to the 17 Jul 1968 DV, while Dionne Warwick was slated to record vocals for the title song, as noted in the 17 Apr 1969 DV.
       In the wake of lackluster reviews, a box-office chart in the 7 Jan 1970 Var listed The April Fools as the twenty-first highest-grossing picture of 1969, with cumulative film rentals of $4.5 million, to date.
       According to the 31 May 1968 DV, Milton Berle was considered for a role. Other items published in DV and LAT between 7 Aug 1968 and 23 Sep 1968 listed the following performers as cast members: Ralph Wainwright; Poupée Bocar; Joe Palma , who was also said to be serving as Lemmon’s secretary; the fourteen-man San Gabriel Valley Eagles ice hockey team; magicians Dai Vernon, Lee Sprague, Nino Guerrero, Bob Fitch, and Jack Adams; Frank Raiter; Johnny Francis; Tommy Strode; John Breckfield; and Thordis Brandt.