Co-star Walter Matthau said after the death of Elvis Presley this about him: ""He was an instinctive actor...He was quite bright...he was very intelligent...He was not a punk. He was very elegant, sedate, and refined, and sophisticated."
James Dean was at one point in the running for the role that, several years later, would be played by Elvis Presley. At this stage, the film was to be a gritty urban drama. Following Dean's death and the casting of Elvis, it was retooled to suit the King.
Dolores Hart, who played Nellie, left Hollywood five years after making this movie to become a nun at a convent in Connecticut. When in 2012 a short, Oscar-nominated documentary was made about her life's unusual trajectory, it was named after a line she says in the documentary about why for her the appeal of a religious life trumped the glamour of her movie career: "God Is the Bigger Elvis."