Cary Grant had announced his retirement from acting in February 1953, stating that, since the rise of Method actors like Marlon Brando, most people were no longer interested in seeing him. He was also angry at the way Sir Charles Chaplin had been treated by the HUAC. He was lured out of his retirement to make this movie, and thereafter continued acting for a further eleven years.
While working on this film in the French Riviera, Grace Kelly met Prince Rainier of Monaco. It wasn't love at first sight for Kelly, but the prince initiated a long correspondence, which led to their marriage in 1956. Afterward, she became Princess Grace of Monaco, and retired from acting.
When Francie (Grace Kelly) parks above Monaco about 1 hour into the film, she points and says "Just look at the colours of the sea down there." Just before her hand drops back down, she very briefly points towards the road which was later renamed Avenue Princesse Grace in honour of Grace Kelly. The road can be seen on the left side of the screen, immediately to the left of the top of the tallest plant in the foreground.
In the scene on the float platform, Danielle makes a point of how much younger she is than Frances. In fact, Brigitte Auber was 4½ years older than Grace Kelly. Danielle is referred to as being a "teenager," but Auber was actually 30 when the film was made.