The Big Mouth marked filmmaker and actor Jerry Lewis’s thirty-sixth feature-length motion picture. It was initially titled Ready, Set Die. Referring to it by that name, a news item in the 3 Oct 1966 DV stated that Lewis hoped to cast professional baseball player Sandy Koufax, and actors Don Drysdale, Maury Wills, and Lou Johnson. Actresses who were under consideration at the time included Nina Wayne and June Wilkinson, the 10 Nov 1966 DV noted.
       The 18 Nov 1966 DV announced a title change to The Big Mouth. Principal photography began shortly after on 5 Dec 1966, with location shooting in San Diego, CA, where Sea World served as a filming site. Production moved in late Dec 1966 to the Columbia Pictures studio lot in Hollywood, CA. An item in the 7 Dec 1966 DV noted that Lewis established a “‘wide-open set’ policy” during the shoot, encouraging members of the public to visit the filming locales. Columbia Pictures teamed with J. Floyd Andrews of Pacific Southwest Airlines to distribute “announcement cards” which invited passengers arriving in California to view the filming.
       Director of photography W. Wallace Kelley had to undergo an emergency appendectomy during production. The 16 Jan 1967 DV reported that he had been replaced by Ernest Laszlo.
       The film debuted in St. Louis, MO, on 21 Jun 1967. An advertisement in the 28 Jun 1967 Var touted the five-day opening at nine theaters around the city as the “biggest Jerry Lewis business ever,” with a box-office gross of $62,100. The picture went on to gross $2 million in film rentals by early 1968, as noted in a 3 Jan 1968 Var box-office chart.
       Costumes for Lewis were provided by Sy Devore, according to an item in the 13 Dec 1966 DV. John Macchia served as Lewis’s double, as stated in the 26 Dec 1966 LAT, and the following actors were listed as cast members in DV and LAT items published between Nov 1966 and Feb 1967: Barbara Burgess; Gayle Hunnicutt; Kathleen Freeman; Charo (a.k.a. Charo Cugat); Harry Fleer; Roland La Starza; Rob Reiner; Col. Harland Sanders; Mike Williams; Iris Ratner; Percy Helton; and Pepper Curtis. A news brief in the 26 Apr 1967 Var noted that Mac St. Johns acted as publicity coordinator.