According to Maureen O'Hara in her autobiography, "Tis Herself", some stunt men died during the shooting of the film when they fell from their horses during a scene in the middle of a muddy river. Their bodies were allegedly never recovered.

John Ford was especially irritated when producer Herbert J. Yates showed up on location with fellow Republic executive Rudy Ralston. Pointing out the time (it was ten in the morning), Yates asked when Ford intended to start shooting; "Just as soon as you get the hell off my set", Ford supposedly replied. The director later played a practical joke on the two producers at dinnertime. He hired one of his actors, Alberto Morin, to masquerade as a French waiter with poor English skills. During their meal, Morin managed to spill soup on the men, break several plates, and create a general ruckus in the dining room but Yates and Ralston never seemed to catch on to the joke.

Of all the shooting locations listed, none are near or on the Rio Grande. It flows only in Colorado, New Mexico & Texas.

John Wayne wore a smaller toupee than usual to make his character look slightly older.

One of the songs performed in this film, "Aha San Antone" was composed by actress, singer and songwriter Dale Evans, who was the wife of singer and actor Roy Rogers. He was at one time lead singer with the Sons of Pioneers who play the Regimental Singers.

Continuity

On the covered wagon carrying Kathleen Yorke during the Indian attack, when the driver falls off, the canvas behind Mrs. Yorke is wide open. Later, when another trooper jumps on to drive the wagon, the canvas is closed tightly.

While the guests are entering the grandstand, one of the troopers being honored is missing (Indian scout). He shows up in the next scene as the last man in line.

As Col. Kirby and his troop approach the Rio Grande, we are shown a wide shot of the river in the distance with no sign of an engagement between the Apache and the Mexican soldiers. As the troop gets closer, we see smoke rising and the Mexican soldiers start to approach the river bank.

In Jeff's ride to fetch "his pappy" after the wagon train is ambushed, his hat is alternately on and off of his head.

After the wagon train is rescued, Sandy Boone remains behind with Mrs. Yorke as the command rides off in pursuit of the captured children. Later, he is present with the troops to be picked by Tyree to sneak into the Mexican village.



Factual errors

The US Flag shown at the beginning is not correct for the time period of 1879-80. The flag shown is the 48 star flag used from 1912-1959 which is when the movie was filmed. The correct flag would be the 38 star flag used from 1877-1890.

A man John Wayne's size would not have been in the US Cavalry of the 19th Century. To be in the cavalry, a man had to be no taller than about 5'9" or 5'10" tall and weigh no more than 155-160 pounds. Smaller men were chosen for the cavalry out of consideration for the horse, which had to carry the man and his equipment. Bigger men became infantry soldiers.

In several scenes troopers are using Winchester repeating rifles. In the 1870's/1880's cavalry used the single-shot trapdoor Springfield rifle.

The pistol that Lt. Col. Yorke uses is a Colt single action with a 4 3/4 inch barrel. The US Army model had only a 7 1/2 inch barrel.



Incorrectly regarded as goofs

When Lt. Col. Yorke is with the Mexicans at the Rio Grande River, he calls the area Rio Bravo and Rio Grande. The Rio Grande River is known in Spanish as Rio Bravo. Since Yorke is speaking to a Mexican military officer and referring to the Mexican side of the river, this would be correct and not an error to do so.



Revealing mistakes

When Lt. Col. Yorke checks his son's height on the tent, you can see previous marks from another take.

Towards the beginning of the movie, when they are at the fort identifying the different "bands" of the dead Apaches lined up on the ground, several of them can be seen still breathing.



Miscellaneous

That the Rio Grande at El Paso is about 500 miles from Monument Valley is more of a production value than an error.

During the horsemanship display an onlooker takes a bite from a plug of tobacco, which doesn't make much of a sound at all. The Foley artist used the sound of someone biting a carrot.



Anachronisms

"You're in the Army Now" was written later (1917) than the time of the movie's actions.

The movie is set in the around 1879-1880, 15 years after General Sheridan's campaign through the Shenandoah Valley. One of the songs in the movie, "Down by the Glenside (The Bold Fenian Men)," however, was not written until 1916.

When the regimental singers are serenading Kathleen Yorke and General Sheridan outside Colonel Yorke's tent there are several lanterns hanging from the top of the opening. The lantern on the right side of the tent post clearly has an electric light bulb in it.

The guitars in the film were far from authentic. One instrument in particular stands out: a classic pre-war Martin D-45 (manufactured between 1933 and 1942), which, by the number of frets, appears to be from 1937 or 1938. Played in this film by Bob Nolan of the Sons of the Pioneers, the D-45 is lavishly inlaid with abalone shell on all edges, front and back, plus around the soundhole. When new, it sold for a price fifty percent higher than a brand new car. As such, it would have been far out of reach for a lowly enlisted cavalryman, even if they had been available in the 1870's. The current new street price is a much more "reasonable" $8,659.00. A pre-war D-45 can sell for $250,000.



Audio/visual unsynchronized

When the guitar is played, it is abundantly clear that the obviously non-musician actor is not playing what the audience is hearing on the soundtrack.

When Recall is sounded after the children are rescued you hear the call blown, then it stops. The horn is still being blown after the call stops.

Troopers while marching are singing 15 Miles on the Erie Canal, except the song was 1st heard in the early 1900s, (Copyright date 1912), NOT during the time frame this move was supposed to be of.

In the Roman Riding section the sound of galloping horses does not match the visual of the animals.

Near the end, after Colonel York is wounded, he tells the bugler to sound recall. The bugler can be clearly seen inhaling several times while the bugle is sounding.



Crew or equipment visible

During the Indian attack on the wagon train, Kathleen Yorke is in the driver's seat of a wagon by herself. There is another person visible in the back of the wagon who has the reins and is driving the wagon.



Errors in geography

When viewing the Rio Grande River from the United States, north bank, the river flows from right to left. The river is flowing the wrong direction.



Boom mic visible

At the end of the scene where Trooper Tyree is arrested (when Mrs. Yorke is complaining about "Yankee justice") the shadow of a boom mic is visible behind Sgt. Maj. Quincannon.

Obvious shadow of boom mic on ground behind Lt. Colonel Yorke, during conversation of Kathleen calling Quincannon an arsonist.