Joshua Logan was anxious to replicate the success of Gigi (1958) and according to Leslie Halliwell insisted on a publicity campaign for "Joshua Logan's 'Fanny' ", until the double meaning was explained to him.
When shooting moved to a film studio in Paris, Jack L. Warner got cold feet about his decision to cut the original musical's songs, and ordered Joshua Logan to shoot two of Panisse's numbers in case they decided to use them. Chevalier performed his first number perfectly, but when Logan tried cutting it into the film, he realized it wouldn't work. When he told Maurice Chevalier, the singer was relieved. He had wanted this to be his first non-singing role in English.
The east side of the port at Marseilles had not been touched in decades, making it a perfect location for a period film like this. But the west side had been rebuilt after World War II. Originally, art director Rino Mondellini got permission from the mayor to put false fronts on the new buildings. When he started drilling holes in the sidewalk for the posts that would support the facades, however, the townspeople objected, and the mayor rescinded his permission. Mondellini called the eighteen holes he had already made "The most expensive golf course in the world".
Marius is 19 and Fanny is 18 at the beginning of the play. In reality, Horst Buchholz was 28 and Leslie Caron was 30 when they played their respective roles.
This production of "Fanny" began as a hit Broadway musical in 1954, with the libretto co-authored by Joshua Logan, who also directed the show, which starred Ezio Pinza, in his last stage role before his death, as Cesar, Walter Slezak as Panisse, and Florence Henderson as Fanny. When the musical was filmed, Logan stayed on as director, and the film was faithful to the show, except for the fact that Logan dropped all of the songs and simply used them as background scoring.