- Acting for Two: Harry Carey Jr. reputedly played two different roles in the film. One was Dan Latimer, who was killed in the stampede. The other was supposedly later in the movie when he (wearing black vest and hat) and John Wayne stood together and Carey spoke the line, "They crossed here . . . "
- Creator Backlash: Montgomery Clift was unhappy that the ending was changed to Dunson living. He also felt that his performance was mediocre.
- Cut Song: The song "My Rifle, My Pony and Me" was originally written by Dimitri Tiomkin for this film, but it was completed too late for use in the scene where a cowboy song was needed, so they substituted another one. However, strains of the song can be heard in the theme music, and the words were changed for use in the later movie. It was later sung by Dean Martin in Rio Bravo.
- Darkhorse Casting: This was Montgomery Clift's first film. Howard Hawks cast him after seeing him on Broadway.
- Hostility on the Set:
- John Wayne and Walter Brennan would not get along with Montgomery Clift for personal, professional, and political reasons and they stayed away from the young actor when not filming. Clift later turned down Dean Martin's role in Rio Bravo because he did not want to be reunited with those two actors.
- Clift did occasionally take part in the nightly poker games that Hawks and Wayne organized where "they laughed and drank and told dirty jokes and slapped each other on the back. They tried to draw me into their circle but I couldn't go along with them. The machismo thing repelled me because it seemed so forced and unnecessary".
- No Stunt Double: In the shot of Groot driving the chuck wagon across the river, Walter Brennan did the stunt himself.
- Playing Against Type: This was the first time John Wayne played an un-heroic role.
- Real-Life Relative: This was the only film in which Harry Carey Jr. appeared with his father Harry Carey, although they have no scenes together.
- Reality Subtext: The tension between Dunson and Garth wasn't down to good acting. There were concerns that John Wayne and Montgomery Clift wouldn't get on due to their politics (Wayne being Right Wing, Clift being Left Wing). Though they agreed not to discuss politics, the two weren't friendly. Clift didn't care for Wayne's machismo, while Wayne, while respecting Clift's talent, once described him as "an arrogant little bastard".
- That said, Clift's performance did encourage Wayne to try harder in his role.
- Romance on the Set:
- John Ireland and Joanne Dru had an affair onset and were later married. This annoyed Howard Hawks, as he was also pursuing her.
- It's rumoured that Ireland had an affair with Montgomery Clift.
- Serendipity Writes the Plot: Despite the reputed lack of rain, there were frequent unexpected downpours on location. John Wayne convinced Howard Hawks to shoot in all weather, and the script was rewritten to accommodate a fierce storm.
- The Shelf of Movie Languishment: The movie was filmed in 1946 but held for release for two years, in part due to legal problems with Howard Hughes who claimed it was similar to his The Outlaw.
- Star-Making Role: For Montgomery Clift.
- Throw It In!: In the scene where Matt tells Tom he's taking over the drive and moving the herd to Abilene, John Wayne turned his back on him and said in a low voice, "I'm gonna kill you, Matt." The action was counter to Howard Hawks' direction to have Wayne cringe, but the actor refused to appear cowardly and played it his way, to Hawks' ultimate satisfaction. The improvised moment left Montgomery Clift dumbfounded and was used in the final cut.
- What Could Have Been:
- Gary Cooper turned down the role of Tom Dunston because he didn't think it fit his screen image.
- Burt Lancaster was offered the role of Matt Garth by agent Charles K. Feldman, who was trying to sign the former acrobat, but Lancaster had just signed with agent Harold Hecht and so turned down the role to star in The Killers, which was his film debut.
- Cherry Valance was supposed to have a bigger role and was written with Cary Grant in mind. Grant turned it down and Howard Hawks disliked John Ireland's performance and the part was greatly reduced.
- Before filming began consideration was given to shooting in color, but Howard Hawks found the processes at that time to be too garish and decided that black-and-white as being more conducive to a feeling of the period.
- The film's original ending had had Tess and Matt escort a mortally wounded Dunston across the Red River, where they stand him up long enough to have him die on Texas soil. Writer Borden Chase vigorously objected to Howard Hawks' change but to no avail.
Trivia / Red River