Fox re-used the music score from The Day the Earth Stood Still (1951) by Bernard Herrmann in this picture, much to his regret. He was outraged, and told the studio executives what he thought of it after he received notice from the Musicians' Union in 1958.
In his autobiography, "The Kid Stays in the Picture," Robert Evans says that this movie had the following working titles: "The Hell-Bent Kid", "Rope Law", "Enough Rope", "Quick Draw", "Quick Draw at Red Rock", and "The Hell-Bent Kid II". This mistakenly created the impression that Evans was appearing in more films than he really was. The final title came from a marketing exec trying to cater to both western and horror film audiences.
In the UK, this was the first western ever to be given an 'X' certificate (i.e., adults only) by the British Board of Film Censors (BBFC).