David Janssen and Rosemary Forsyth fell in love during the filming of this movie.
Debut of actress Brenda Vaccaro.
This was the first feature film Garson Kanin had directed for the cinema in 28 years. He then went straight on to direct another movie, "Some Kind Of A Nut", which appeared only a few months later; after that, he never directed films again.
Throughout the movie's casino scenes, an employee is paging persons on the public address system. One person paged near the middle of the movie is "Jay Sarno," the man who built Caesar's Palace and the Circus Circus Casino.
In an interview,director Garson Kanin said that he had intended that Cary Grant and Warren Beatty play the roles later given to David Janssen and Robert Drivas.