Edward G. Robinson wrote in his autobiography, "In the film I played Lancey Howard, the reigning champ of the stud poker tables...I could hardly say I identified with Lancey; I was Lancey. That man on the screen, more than in any other picture I ever made, was Edward G. Robinson with great patches of Emanuel Goldenberg [his real name] showing through. He was all cold and discerning and unflappable on the exterior; he was ageing and full of self-doubt on the inside....Even the final session of the poker game was real...I played that game as if it were for blood. It was one of the best performances I ever gave on stage or screen or radio or TV, and the reason for it is that is wasn't a performance at all; it was symbolically the playing out of my whole gamble with life."
Edward G. Robinson said of Steve McQueen, "He comes out of the tradition of Gable, Bogie, Cagney, and even me-but he's added his own dimension. He is a stunner..."
Joan Blondell was trained for her role as Lady Fingers by master card trickster and technical adviser Jay Ose.
Sharon Tate was replaced in the film by Tuesday Weld after Sam Peckinpah was fired by producer Martin Ransohoff.
When Steve McQueen was first told that Paddy Chayefsky was writing the script, he reportedly said, "Tell Paddy when he's writing that I'm much better walking than I am talking." Chayefsky's version of the screenplay was not used. The film was being re-written during filming.