Leonard Nimoy mentioned this film in both of his autobiographies because it gave him a chance to break away from his role as Spock on Star Trek (1966). He mentioned that the time he made the film was one of the happiest of his life, even though his part was rather brief.
Both Yul Brynner and Leonard Nimoy were the subjects of anti-smoking TV commercials after death. Brynner when he was near death in 1985 filmed an ad telling the audience he was gone because smoking led to his cancer; while Nimoy's widow Susan Bay Nimoy (married to him since 1989, his first wife having been Sandi Nimoy from 1954 to 1987) appeared in an ad showing Nimoy with a respirator since smoking led to the chronic obstructive pulmonary disease which took him way too soon even at 83, saying we always think we have so much time, and we really don't.
The General's (Jose Nieto) voice was dubbed over by Ricardo Montalban, not a strange thing if producers thought the original actor's accent was too thick to understand.
In Catlow (1971), Leonard Nimoy plays a bounty hunter who carries a Winchester Model 1892 "Mares Leg" Rifle as his main weapon, in a tribute to the TV Western series, Wanted: Dead or Alive (1958), in which Steve McQueen's bounty hunter used as a main weapon.