Goofs

When Billy hands Alex the picture of himself, Billy's thumb is by his head in the photo. When he drops his arm, he is holding the picture by the feet.

When the Regulators arrive at the village of Juarez, Billy is wearing a white shirt and a dark vest, and his long coat is tied down behind his saddle. A moment later, as the villagers chant "Chavato", Billy is wearing the coat.

Doc's hat during the shoot-out at the brother by the river.

The position of the three knives thrown at Billy.

A character remarks that none of the Regulators are over 21. Even excluding the Regulators omitted from the film, Billy the Kid was the only one under 21. Chavez was 26 during the events of the film, Charlie was 30, Doc was 29, and Richard Brewer was 28.

At Tunstall's burial, Richard holds a Bible and reads "in so much as it pleaseth Almighty God..." The funeral rite is in the Book of Common Prayer, not the Bible.

The circumstances of John Tunstall's death in real life are very different from the film. Tunstall feared for his life and likely was in the process of surrendering when he was murdered by the deputies who pursued him.

At the start of the Kid's introduction to the regulators, it is explained to him that "you can't be any geek off the street." The term 'geek' in any form wasn't coined until around 1915.

During the New Year's Eve dance, McSween tells Tunstall that the Murphy faction had provided the Governor of the new Mexico territory with a 'fat campaign contribution. Territorial governors were appointed, not elected, and would not have needed campaign funds.

Late in the movie, Doc stands up during the gunfight and bumps the brick chimney. It bounces as though made of rubber.

In the beginning of the movie when Billy is first taken in to the ranch it appears he's getting ready to shoot a pig. As he takes aim, the sun shines through the barrel from behind, making it obvious that the gun is not loaded.

In the final battle, Billy is shot in the left arm. Sparks emerge from the rig that makes the explosion.

In the beginning of the movie, just after it's shown Billy is running, there is a quick scene showing two men fighting. If you look closely, you can see when one of the men swings he misses the other man completely, yet the man still falls down.

During the final gun battle, Dirty Steve asks, "Where's Chavez"? Casey Siemaszko's stunt double says, "I don't know, he must have skinned out."

Chavez calls Billy a "chivato" which he does repeatedly for the rest of the movie. According to Google, "Chivato" means rat or traitor. With that in mind, most of the times Chavez says this word, it makes zero sense in the context of them being "Pals."

Chivito in Navajo means "baby goat" A baby goat is a kid...

The men in the cantina sing "When Irish Eyes Are Smiling," which was written 34 years after the events of the film took place. The composer of the music, Ernest R. Ball, was born the year of the same events.

The "sad ballad" that Billy whistles to let Texas Joe Grant know that he is in fact Billy the Kid is Seán Ó Riada's "Mná na h-Éireann" ("Women of Ireland"), written in the early 1960's.

Black and white soldiers fire side-by-side in the battle at McSween's house. The US military was segregated until 1948. While black units had white officers, it's clear from the number and position of the white soldiers that they can't all be officers.

During the opening credits, at least two characters firing in the line pull Smith & Wesson Model 1899 Military & Police double action revolvers. They were introduced in 1899, 21 years after the events portrayed in the film.

As the Regulators are returning home from the New Year's dance, they shoot at a bunch of pheasants. Pheasants did not live in Lincoln County, NM, nor were they prevalent in the US during the Lincoln County War, 1878-1881. Pheasant pairs were released in 1881 in Oregon, and propagated from there.

During the shoot-out with Buckshot Roberts, a (camera) tripod is clearly visible behind Dick Brewer as he takes refuge behind the wood pile; on the right side of the screen.

A crew member's hand is visible, making Dirty Steve's horse react to the gunshot.

Dick and Billy have their guns pointed at one another during an argument at the dinner table when the camera cuts to Chavez watching what is going on. An unknown man with a mustache, in a white shirt with a black vest and a cowboy hat, is also behind him, watching what is going on.

When the boys take Peyote the head of a crew member in sunglasses can clearly be seen while Dirty Steve is standing on a rock just before he jumps off and shoots.

Terrence Stamp was 50 years old when the movie was filmed. The real John Tunstall was 24 years old when he was murdered.