- Alan Smithee: Due to being under contract with another film company at the time, Ennio Morricone used an alias, "Leo Nichols", and submitted a score for the film. These days, it's attributed to his real name than the alias
- Contractual Obligation Project: Burt Reynolds only agreed to make this film because he was under the impression that Sergio Leone would be directing. When he found out it was Sergio Corbucci he tried to pull out, but the contracts had already been signed and it was too late.
- Edited for Syndication: Several seconds of the film were edited out for TV airings, including a shot of residents in Esperanza watching a round of cockfighting, and part of the first chase of the film (when Duncan's men are chasing the showgirls) that ends with the horses being shot and falling down at a painful-looking angle, with their front legs buckling in and their heads hitting the ground. These shots were restored for the DVD release.
- Follow the Leader: Dino De Laurentiis made this spaghetti western with the intention of replicating the success of A Fistful of Dollars after that movie had become a box-office hit. He wanted to find an American actor to rival Clint Eastwood's popularity. Burt Reynolds had appeared in TV westerns and was part Cherokee Indian. De Laurentiis persuaded him to sign on.
- Hostility on the Set: Burt Reynolds and Sergio Corbucci didn't get on at all. During the production, Corbucci reportedly drove Reynolds deep into Spain's Almerian Desert and then drove off leaving him there to walk back to town.
- No Stunt Double: A former stuntman, Burt Reynolds supervised the stunts on this picture.
- Old Shame:
- Burt Reynolds did not look on the film fondly, having been tricked into getting involved because he believed he would be working for Sergio Leone (creator of several successful spaghetti westerns at that point) instead of Sergio Corbucci. He later commented that he "wore a Japanese slingshot and a fright wig", and claimed that the film was "so awful, it was shown only in prisons and airplanes because nobody could leave."
- Nicoletta Machiavelli (Estella) also complained about her role in the film. She claimed that she wasn't happy with the miniscule amount of dialogue she was given and didn't have enough to do, despite being the top-billed female star.
- Troubled Production: Pre-production on the film had some challenges, as Corbucci's plan of casting Marlon Brando in the role of Joe fell through and he tricked Reynolds into getting involved as the main lead. Reynolds joined the film thinking he would be working for a different Sergio (Leone), and was left stranded on the first day on set after Corbucci drove him out into the middle of the Almerian desert to meet a local family, then packed up the crew and moved elsewhere while he was gone. Reynolds also skipped out midway through production to film a commercial before returning, clearly realizing at that point that he had bigger priorities (and rising star power) than Corbucci believed. For their part, both Reynolds and Nicoletta Machiavelli (who played Estella) both disowned the film afterwards, claiming it was amateurish and didn't give them enough to do.
- Working Title: A Dollar a Head.
Trivia / Navajo Joe