Fred Astaire's character is based on photographer Richard Avedon. In fact, it is Avedon who set up most of the photography for this film, including the famous face portrait of Audrey Hepburn unveiled during the darkroom sequence.
Ditzy model Marion is played by Dovima, who was one of the top fashion models of the day and often worked with Richard Avedon.
Ditzy model Marion's interest in comic books was inserted into the film to reflect actress-model Dovima's real-life passion for them.
In order to secure Audrey Hepburn and Fred Astaire in the cast, producers told each that the other was already signed, figuring they would not pass up the opportunity to work together.