Goofs

After Calvera and his men are driven from the village the first time, three of his men start taking potshots at the villagers from the trees. One shot strikes Chico's hat and knocks it off his head. He even sticks a finger through the hole after retrieving it. A few minutes later, Petra (the Mexican girl) is talking with Chico, and the bullet has disappeared.

The first man Calvera kills near the beginning of the movie has no wounds on his back after being shot and falling to the ground. When the villagers run to the body to look at the man, two wounds are on his back.

When Chris and Vin begin driving the hearse up to Boot Hill, they pass the Belmar Hotel sign twice; once silently at the very start, and again as they briefly discuss the towns they've come from a few moments later.

When Calvera and his gang first ride into town in the beginning of the movie, they take chickens and food. When they ride out of town, they don't have any loot with them.

Just before the first confrontation with Calvera, Chris removes the loop holding the revolver in his holster twice.

Vin tells a humorous story to Chris and the Old Man, and mentions a fellow back home falling off a 10-story building. The film is set in the 1870s, the first 10-story building was Chicago's Home Insurance Building, built in 1885.

After the first gun battle between the Seven and the gang, Britt empties his revolver, presumably of spent casings, however he shakes out the rounds instead of using the ejection rod. The spent casings fall freely from the cylinder; they would have swollen during firing.

In some prints, Natividad Vacío who plays Miguel, is listed as Tomas, while John A. Alonzo (billed as John Alonso) who plays Tomas, is listed as Miguel.

The whistle Bernardo gives to little girl has a fipple, but he turns it down when he blows into it. It's visible as he finishes making the whistle.

When Bernardo pulls one of the village boys onto his lap to spank him for calling the adult villagers "cowards", the bed appears to collapse beneath him.

When Britt duels with the cowboy, the steam engine in the background is completely cold. No smoke rises from the chimney and no steam is coming out of the safety valves. The freight cars are loaded with cattle, and the crew is apparently waiting for departure orders. Steam locomotives took hours to warm up, and were rarely shut down completely.

Whenever a main character dies during the final battle, the gunfire disappears while they speak their last words or die slowly.

When two peasants drop rocks on the ground, the way they fall and roll reveals that they are fake.

Steve McQueen wears Levi's jeans with the famous red tab, which were not introduced until the 1930s.

Britt's knife appears to be a stiletto switchblade (automatic opening knife with locking mechanism). This kind of weapon was not imported from Italy until the 1950s.

Charles Bronson wears a denim shirt. Denim trousers had been around for many years, but denim shirts weren't manufactured until the 1920s.

The outline of a pack of cigarettes and (possibly) a Zippo lighter are visible in Yul Brynner's shirt pockets.

The movie appears to be set sometime in the mid-to late 1890s. All of the main characters wear low-slung, Buscadero-style holsters, which were basically unknown before the early 1900s. Belt guns in the "Wild West" era were worn at the belt line, usually in cross-draw holsters as they were both more comfortable to wear and easier to draw from while mounted on a horse.

An additional "slap" sound happens shortly after Bernardo finishes spanking the village boy.

The echoing gunshots make no sense in a movie that takes place in a valley.

Calvera says he has 40 men. Chico could not have blended in with a group so small, especially when he had a conversation with Calvera.

After Calvera's first visit near the opening of the movie, the boom shadow clearly moves from right to left as Sotero turns while addressing his fellow villagers.

Chris tells Harry Luck that the job pays a gold eagle plus room and board. The payment offered was $20. An eagle was a $10 gold coin, a $20 gold coin was a double eagle.

When talking about what food the villagers are providing the Seven, Bernardo, who is supposed to be Hispanic, pronounces the word enchilada as though it were French.

At the start of the last shootout, Vin draws and fires on the bandito to his left in the doorway, then fires two more shots directly ahead. Three bad guys are sitting at the wall; if Vin was being thorough, there should have been a fourth shot.

When Chico visits the bandito camp, he is wearing two bandoliers loaded with pointed-tip rifle bullets, as are some of the bandits. They all have Winchester rifles, which require flat-tip bullets.

Chico taunts the red "toro" like a Spanish bull fighter. It's actually a cow with horns.