The car driven by Richard Kiley throughout the film is a Pegaso, an expensive Spanish-made racing/sports car.
Director Don Siegel was so unhappy with the way this film turned out that he later said, "If I knew the Spanish word for 'ech!', I'd use it".
The film was made on location in Madrid using the same cameras and auxiliary camera equipment as "Funny Face". Paramount had shipped the equipment from Los Angeles to Paris, then held it over in Europe for this production after the Fred Astaire/Audrey Hepburn project had wrapped.