Henry Mancini said that although the scoring was the most difficult in his career, the music he composed for this movie was always his favorite.
Several biographies of Audrey Hepburn state she was very nervous shooting her first nude scenes for this film, particularly a skinny dipping sequence. If such a scene was shot, it didn't end up in the final print.
Audrey Hepburn does not wear her trademark designer clothes by Givenchy in this film. Director Stanley Donen insisted that it was essential for her character that she wear clothes that could be bought in a store.
Is one of the very few films in which Audrey Hepburn uses profanity. She says "damn" and "bastard" over the course of the film.
Audrey Hepburn and Albert Finney were required to "direct" themselves in several sequences where they were shown inside of a moving automobile. They pushed the camera's buttons while director Stanley Donen rode alongside them in another car.