- California Doubling: As expected in a John Ford Western, the southern Arizona location is represented by Monument Valley, Utah.
- Completely Different Title: In France, the film was released as The Infernal Chase. In Sweden, it was called Laglöst land, meaning Lawless Land. In Spain, it was called Pasión de los fuertes, which roughly translates as "Passions of the strong ones".
- Enforced Method Acting: Walter Brennan, John Ireland, and Grant Withers were required to do their own riding and shooting in the scene where the clan rides into town during a dust storm. John Ford used a powerful wind machine and told the actors to fire their guns close to the horses' ears to make them ride wild.
- Executive Meddling: Darryl F. Zanuck forced a reluctant John Ford to film the final kiss between Wyatt and Clementine.
- Fake Nationality: Linda Darnell (American, non-Latina) as Chihuahua (presumably Mexican, though at least one commentator has referred to her as "Apache").
- Hostility on the Set: Walter Brennan disliked John Ford so much that he never worked with him again. One time when Brennan was having a little trouble getting into the saddle, Ford yelled, "Can't you even mount a horse?" Brennan shot back, "No, but I got three Oscars for acting!"
- Playing Against Type: Walter Brennan in a rare villainous role as Old Man Clanton.
- Real-Life Relative: John Ford's elder brother Francis Ford appears in an Uncredited Role as an old soldier.
- Real Song Theme Tune: The song "My Darling Clementine" is used over the opening credits and throughout the score.
- What Could Have Been:
- The first draft of the script is fairly close to the final movie, with some crucial differences: the draft has Doc Holliday killed before the gunfight; the Clantons never overtly confront Earp; Chihuahua is killed but it is another wounded girl who is operated on by Doc, and Wyatt leaves at the end with no final parting words to Clementine.
- James Stewart was Daryl F. Zanuck's first choice for Doc Holliday, but he turned it down in order to star in It's a Wonderful Life. Douglas Fairbanks Jr., Tyrone Power and Vincent Price were also considered.
- In the mid-'80s a remake was announced with Burt Reynolds and Tom Selleck, but it never materialized.
Trivia / My Darling Clementine