Maureen O'Hara wrote in her autobiography that the famous climactic spanking scene was completely authentic and that John Wayne carried it out with such gusto that she had bruises for a week.
When John Wayne needed 500 longhorn steers for a key scene, the Mexican government lent them to him. Mexican longhorns' horns tip up, as opposed to American longhorns, whose horns tip down.
John Wayne insisted that the role of the weak, insipid Governor be called "Cuthbert H. Humphrey" with the intention that he be seen as a parody of liberal Sen. Hubert H. Humphrey, whom Wayne intensely disliked.
Although often seen as simply a knockabout comedy, John Wayne also intended the film to be a statement of his own political views, his disapproval of the negative representation of Native Americans in previous westerns he had no creative-control over, and his disapproval of wife-beating and marital abuse from either spouse.
The "mudhole" in which the famous brawl took place was made of mud consisting of bentonite, a type of clay which is used in the drilling of oil wells and has the consistency of chocolate syrup. According to Leo Gordon (the first one to be knocked down into it), that scene took a week to shoot.