The pimps' union is called the "Mec's' (tough guy's) Paris Protective Association" (MPPA), which also stands for "Motion Picture Producers Association", an organization which had given Director Billy Wilder some trouble.
Shirley MacLaine was not happy with the script, and thought even less of the film after it was finished, calling it "crude and clumsy". She was surprised to get a Best Actress Oscar nomination out of it, saying, "I would have been nonplussed had I won it."
Charles Laughton was writer/director Billy Wilder's first choice to play Moustache. Laughton, who had given an Oscar-nominated lead performance under Wilder's direction in Witness for the Prosecution (1957), agreed to play the role, but died before principal photography commenced.
In order to be able to play Irma properly, Shirley MacLaine traveled to Paris to see what it was like for real Parisian prostitutes. They were eager to tell her what it was like, and very willing to answer any questions she had. When asked if she would like to "watch them in action", she politely declined, but to her surprise they became indignant. They requested that she watch one of their weekly customers with three of the girls through a small window in the hotel door; she unwillingly obliged.
Production designer Alexander Trauner imported all the window glass used in the sets' windows from France, as well as materials (iron for railings) used in the sets' construction. The window glass was imperfect--wavy, with air bubbles. All the street shop windows, apartment mullioned windows, were cut from this imported glass. Parisian street lamps, street fire hydrant plumbing hardware, as well as the sets' hardware for door latches, window latches and locks, were air-lifted to the U.S. and delivered to the Goldwyn Studio. These items were matched, molded and fabricated in the film's staff shop, duplicated in fiberglass. The "L" plan of the three streets converging at the central street core conversion at the "Cafe Moustache" was designed in a theatrically forced perspective plan layout. The left side of the street extended through an adjoining stage door. The "T" plan of the central street extended to the rear stage wall, extremely forced in perspective. Miniature French "toy" cars, approximately three feet long by 15-18 inches high, were maneuvered on wires. The false perspective street raised in height above the stage floor approximately three feet. Scenically, the street's façade of shops were scaled and painted to recede as calculated for the reduced perspective horizon plane. Illustrator Harold Michaelson, a genius at laying out perspective, calculated all of the perspective plans and elevations for the three street ends. The extras hired for "atmosphere" were small actors and actresses for all background action shots. Rain pipes were hung over the entire street set for the rain sequences, with the street's gutter system planned to flush the water out of the stage through stage-wall drainage systems into the exterior adjacent studio street. The second-story atelier set was located on the same stage, situated behind the street façade. This set was 20 feet off of the ground, accessed by ladders. Forklifts were used to deliver camera equipment and lighting equipment. The cast and crew had to use the ladders to climb up or down, to and from the set. A minimum crew were allowed on the scaffold set with Jack Lemmon, Shirley MacLaine and Billy Wilder. While filming their scenes in this small environment, the wonderful rapport among Lemmon, MacLaine and Wilder was a "very private funny scenario". Behind this set, the scenic shop department was located on the stage rear wall, with a paint frame and a 20-foot-high deck, from which the scenic artists worked, while painting the film's scenic drops. Additional stages were used for the "Les Halles" and the cathedral interiors. The beef carcasses, used for set dressing in the meat market, were white plastic formed vacuums completely assembled. Twenty scenic artists painted these carcasses with oil paints, using sponges and fine-hair paint brushes. They employed scenic techniques to reproduce fresh marbled fat-grained meat. All of the cathedral stained glass leaded windows were also scenically oil-painted on imported French glass.
The original Broadway production, the musical version, opened at the Plymouth Theater on September 29, 1960, ran for 524 performances and was nominated for the 1961 Tony Award for the Best Musical. The only Tony won was for the performance of Elizabeth Seal in the title role. Keith Michell's role, played by Jack Lemmon in the film, was not that of a policeman, but a law student. Clive Revill, who originated Lou Jacobi's part as the barkeep, earned a Tony nomination as well. All of the Broadway songs by Marguerite Monnot were scrapped for the film, which was not presented as a musical at all. One song, the lush and romantic "Our Language of Love", did become the centerpiece and theme song for the film, whose score was composed by André Previn.
The trivia item below may give away important plot points.
The Seine River was heavily polluted at the time of shooting. For the scene where Lord X emerges from underwater, Jack Lemmon had to be given several immunization shots, including tetanus, before entering the water. He later said it was the most disgusting thing he had ever had to do in a film.