When Sgt. Quincannon (Victor McLaglen) is addressing the troops and warning them to "watch them words," he asks who owns a dog that had wandered over and was watching the assembled soldiers. Not receiving an answer, he concludes, "Nice dog! Irish setter!" The scene was improvised on the spot by director John Ford. The dog was an unnamed Navajo pet that had fallen asleep during the setup. Multiple takes were required because McLaglen kept blowing the line, calling the dog a "cocker spaniel."
The exterior shots of Capt. Brittles' quarters and the building where Maj. Mac Allshard, Commanding Officer Fort Starke, has his HQ are still standing and in Monument Valley itself near the town of Kanab. The HQ building is now a museum and both are open to the public.
As the regiment's blacksmith, named "Wagner", is seen at work, we can hear the orchestra playing the "Nibelung"-motif from Richard Wagner's famous opera, "Siegfried". In the opera the motif is connected with the forging of Siegfried's sword.
The horse that Ben Johnson rode in this film was a famous movie horse used by many stars in many 1940s and 1950s westerns. It was a big sorrel stallion called "Steel" and was owned by Johnson's father-in-law, Clarence "Fat" Jones, who ran one of the most successful horse-renting stables in Hollywood. The horse, which was known for being very quiet but flashy, was ridden by John Wayne in Tall in the Saddle (1944) and The Conqueror (1956), Gregory Peck in Yellow Sky (1948) and Randolph Scott in The Tall T (1957). The horse made stars look like good riders and Fat Jones always that insisted if "Steel" was used in a movie, the company hire every other horse used in the movie from his stable, so "Steel" was worth a fortune to him. "Steel" had his own double and the horse that Johnson rides in the galloping scenes was not "Steel" but a spectacular galloper called "Bingo". "Steel" was no movie prima donna, however. Johnson also rode him when he won his world champion calf roping title. He also rode both "Steel" and "Bingo" in Wagon Master (1950).