According to an article in the 21 October 1962 edition of the New York Times, the sprawling Rue Casanova set took three months to build at a cost of $250,000 ($2.6M in 2024), and included 48 buildings and three converging streets.
The pimps' union is called the "Mecs (Guys or Blokes) Paris Protective Association" (MPPA), which also stands for "Motion Picture Producers Association", an organization which had given Director Billy Wilder some trouble.
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 Testigo de cargo (1957), agreed to play the role but fell ill and was then hospitalized before principal photography commenced. He died 15 December, 1962. Wilder - who regarded Laughton as the greatest actor in the world - had been aware that Laughton's condition was terminal, but still encouraged the actor to prepare for the role, in part to prevent him from falling into despair. Hence, when Laughton died, he had a luxuriant moustache, which he had grown for the part.
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."