Blooper

When Mississippi throws a chair against the saloon window, the chair breaks the glass and bounces back to the porch when seen from the outside, but goes all the way through the glass and pulls the drapes down with it when seen from the inside. Also, the outside shots show there are shades covering the upper parts of the windows, but there are no shades visible when seen from the inside.

After Cole shoots the gun out of Milt's hand in the saloon, he tells Pedro to "Drop it!". When he does, the gun hits the floor and bounces under McCloud's table. When Pedro leans down to pick it back up, it is on the floor back in front of him.

As Cole and Mississippi shoot at the men on horseback, J.P. is getting ready to come out of the jail on the right side of the screen with a cowboy hat on his head. In the next shot, no cowboy hat is seen.

Bull's position changes between shots as Cole loads J.P.'s gun and the group gets ready to confront Jason in the saloon.

When they are getting ready to confront Jason in his Saloon, not only does Bull's position change between shots, but the position of the guns he is holding changes as well.

Cole was shot in the lower left side of his back where the bullet lodged near the lower left side of his spine. The nerves controlling Cole's gun hand and arm exit the upper right side of the neck, just above the shoulder, so the injury from the bullet wound could not possibly affect Cole's gun hand or anything on his right side to the extent portrayed in the movie. There is nothing connecting the lower to the upper back that could cause that kind of effect.

When Mississippi dresses like a Chinaman he puts an upside down dish on his head. When he hits the guard at the door, the dish flies to the ground. When the camera switches, the "hat" is nowhere to be seen.

During the Battle at the church covering while the others advanced, Bull fires his entire rifle magazine. After rejoining them Bull continues to fire, without a pause to reloading.

The notes played by Bull would only be possible in a valved instrument such as a trumpet or cornet, and one would think they could not be played on a bugle. This is not true. An extremely adept musician with an enormous amount of practice can do this.

When Mississippi test fires the shotgun it changes from an outdoor (on location) shot to a movie studio background plate on James Caan's close up of shooting the gun and back to location for the wide angle. Also, in the close up of the shot of Mississippi shooting the gun, it appears as though an animated gun flash has been added.

When Cole is heading back to El Dorado after meeting Mississippi, and falls off his horse, he braces his fall with his paralyzed right arm.

When Mississippi test fires his new double-barreled shotgun, the horses do not react to either the supposedly loud bang or the bright muzzle flash, despite being only a few feet away, showing these effects were added to the scene later.

Bull carries a .56 caliber Colt 1855 Revolving Carbine throughout the film. This rifle is 5-shot cap-and-ball and very slow to reload. Before, and during the shootout at the church Bull fires more than 10 shots very quickly, without the minutes it takes to reload.

When McCloud exits the cantina and tells Milt and Pedro to come out of the shadows and drop their guns, they come from the right and reenter the cantina. Next, when Thornton tells Mississippi to pick up the guns, he walks straight, nowhere near the direction the men came from.

The film is set a few years after the American Civil War. Several characters, including Thornton and Harrah, use Winchester rifle models that were not introduced until 1892.

In the sheriff's office after Cole is treated for his buckshot wound, during the exchange between him and J.P., the lamp, sitting on the desk behind J.P., has a power cord running atop the table.

When Cole and Mississippi are in the Swede's shop and he bends down to pick up the ammunition for Mississippi's gun, there is a pack of Prince Albert and Bugler tobacco on the shelf behind him. Prince Albert tobacco was not introduced in the United States by the R. J. Reynolds Tobacco Company until 1907 and Bugler not until 1932.

When the Bull character first makes his appearance, there's a small band playing in the background. One of the guitar players is using an archtop style guitar that wasn't made until the 1920s.

When Cole meets Mississippi outside of the cantina and complains that he has not had his supper, several of the lanterns behind Cole contain incandescent light bulbs.

Joe the piano player is clearly just patting the keyboard; his hand motions do not match the music on the soundtrack.

After Mississippi dives under the horses, Cole's lips can be seen to be moving, but he isn't saying anything.

The bugle that Bull plays is a 4 note horn, which in reality cannot play some of the songs that Bull plays on it throughout the movie.

As Mississippi drops in front of the horses riding through town, a rectangular outline can be seen in the dirt below him, presumably filled with softer material to ease the impact of the fall.

Saguaro Cacti do not grow in Texas. They only grow in Arizona, Sonora, and the immediate borders of those states.

During the Battle at the church covering while the others advanced, Bull fires his entire rifle magazine. After rejoining them Bull continues to fire, without a pause to reload.

The first night that Cole and Mississippi arrive in El Dorado, Cole tells Maudie and Bull not to let folks know he is back in town. Yet between these two incidents, Cole and Mississippi go to the jail to see JP. As they approach the jail, Bull stops them and Cole yells out he's "Cole Thornton". Not the best way to keep your arrival quiet.

McLeod's gang would have immediately killed Mississippi after he had been knocked unconscious.

After giving J.P. Harrah the alcohol cure (about 1:15:00), Cole and Mississippi approach the jail from the street. Cole stops and yells to Bull that they're coming in. At this point in the movie, there's no reason to do so; Bart Jason hasn't been arrested yet.

After Cole's been taken by McLeod's men and Maudie and Mississippi return to the jail to explain to JP and Bull what happened, the scene starts with Mississippi telling what happened. From there, Maudie begins talking. In the middle of her explanation, Mississippi mutters "From there on, Maudie's gonna have to tell you what happened after because..." He gestures to indicate he was unconscious. This seems like a needless thing to say given that he had already explained he was knocked out and she was already taking over the retelling. It seems that Charlene Holt jumped into her dialogue too soon before James Caan had finished, since she jumps in at his pause.

When Cole takes Luke McDonald home, he tells Kevin McDonald that Luke told him he fell asleep. When Cole spoke to Luke he did not tell him this.

Cole Thornton describes the hired gun, Nelson McCloud, as tall and dark, with a scar on his cheek. Nelson actually has brown hair and blue eyes with light skin. The wound that left a scar also disfigured his eye, which is a most distinguishing characteristic.

From the time Thornton Cole meets the drunken sheriff, until the time the sheriff sobers up, almost 24 hours have passed. It would seem that if the sheriff just slept it off, he would have sobered up faster than with the hangover concoction that was given him by John Wayne's character.

When Cole and Mississippi are eating dinner right after meeting, Mississippi is talking about his past. He mentions that he had to sell Johnny Diamond's gold watch a while back, indicating that he's broke. Yet when Cole and Mississippi go to see "the Swede", Mississippi has the money to buy a double barreled shotgun and five boxes of shells.