Director John Ford, who in his youth had known the real Wyatt Earp, claimed the way the OK Corral gunfight was staged in this film was the way it was explained to him by Earp himself, with a few exceptions.
Actress Jeanne Crain was scheduled to play Clementine. Studio head Darryl F. Zanuck ruled against her, writing in a memo that the part was so small, Crain fans might be disappointed by not seeing her in more scenes. That's how contract player Cathy Downs got the part instead.
An alternate "preview" version of this film exists. In the 1970s, 20th Century Fox donated some film to the UCLA Film Archives. In 1994, it was discovered that the UCLA print was different from the one being shown on TV. It was about 8 minutes longer with minor variations throughout and a slightly different ending. Both this archival 103 or 104 minute version and the 97 minute release version are included on the Fox DVD released on January 6, 2004.