Carroll Baker, who played George Peppard's stepmother, played his mother two years earlier in How the West Was Won (1962). Peppard is almost three years older than Baker.
The early life of Alan Ladd's character Nevada Smith, was made into the feature film Steve McQueen starring Nevada Smith (1966).
Once considered so racy it was advertised as being "for adults only", this film was re-released in 1972 and submitted to the MPAA for a rating. Indicating how much standards had changed in nearly a decade, it was given a PG.
Filmed in 35mm, this was one of the first films to be blown up to 70mm for its premiere screening.