Visible crew/equipment: In the last scene, when they are riding alongside a river, shortly after the harmonica player changes songs, there's a closeup of John Wayne and appearing from the right on the other side of the river, a pickup truck appears, and then they quickly cut to different characters. (01:56:55)
Continuity mistake: When Abbott and Costello are on the train. Costello walks over to see the guys playing poker. In the background a man closes the back door of the train. As Costello passes you see the door is open again and the same guy closes it again. (00:17:10)
Factual error: While the Confederate captain is explaining the mission, a couple of the "patriots" are inserting cartridges into their Colt Peacemakers. A neat trick, since the Civil War ended in 1865, and the Peacemaker wasn't introduced until 1873.
Factual error: The song that Davy Crockett plays on the violin is 'The Mockingbird Quick-Step,' written in 1855, several decades after the events of this movie (and later used by the 'Three Stooges' as a theme song.).
Continuity mistake: After the Baxter/Rojo dinner, the background changes from nightime to daytime at the cemetery, then back to nightime again when Clint kidnaps Mirasol.
Visible crew/equipment: In several scenes there are rectangular arrays of studio lamps visible, reflected in the actors' space helmets.
Factual error: The movie depicts Wes Studi, who is playing the Paiute medicine man "Wovoka," as coming to the Sioux reservation and delivering his vision. Wovoka (aka Jack Wilson) was from Schurz, Nevada 1250 miles away from the Pine Ridge Reservation in South Dakota. He never travelled to South Dakota. What really happened was tribal parties (at great personal risk) travelled to Nevada to get the message and brought it back to the Sioux people. Of course, this message was "modified" somewhat to better fit Lakota culture.
Audio problem: When Bunny (Ramon) is, as Zorro, spelling out "Zorro" on the wall with his whip, the number of whiplash sounds does not match the number of marks in the wall.
Continuity mistake: When Mitch is trying to find the hand, Glen grabs the map. When he grabs the map there is a hole in it, but before he sets it on fire, the hole is gone.
Continuity mistake: This is actually in a deleted scene on the DVD: Jones shoots a mountain lion at night, and it's seen to be completely dark out. The two other men go out to look at it, but when they're walking across the snow, the sky is suddenly pale blue and there's light just below the horizon. It looks like it's just before dawn or just after sunset. But when they reach the dead mountain lion, the sky is suddenly black again, and it looks like it's the middle of the night.
Revealing mistake: When Howard and Curtin chase Dobbs, they pass a dead donkey which is obviously breathing, and the rope used to tie its legs together is visible too.
Factual error: Tombstone is nowhere near Monument Valley.
Audio problem: The Rabbi's horse is bucking in reaction to the rattlesnake, and all the while the Rabbi is yelling in Yiddish - but his mouth is not moving.
Continuity mistake: After the scene where Sara and Maria tie up Quentin and take pictures of him naked, when they are leaving the hotel with Quentin tied up, Sara's hair is just below her shoulders, but the whole movie her hair is to her waist.
Revealing mistake: Early in the movie, there is a visible circular, plastic looking effect on Gideon's arm as he removes the bullet with the knife. This is more noticeable around his shoulder when he cauterizes his wound with the hot knife.
Factual error: During the final shoot-out, when Raf shot the man on the roof as he enters town, the wrong flag is displayed - a 48 star flag, but the time setting is the 1880's, when there were fewer states.
Continuity mistake: In the scene towards the end of the film, when three troopers creep into the church, Margaret Mary hits Sandy over the head. When Margaret Mary starts to speak, a ribbon around her neck curiously unravels itself and disappears behind her back .
Revealing mistake: When The Indians launch their final attack (towards the end of the film), on a old outpost held by a small group of soldiers, Ward Bond is hit by a arrow which enters the right side of his chest. In the next shot you see Gregory Peck removing the arrow from the left side of Ward Bond's chest.
Factual error: When the trappers first encounter the Rickarees, the bow cannon is discharged, creating an explosion near the Indians, who promptly turn and ride away. Immediately after, a second shell explodes near them. It would be impossible for a single gunner to sponge out and reload with cartridge and ball in the space of 10 seconds.
Factual error: In one of the train cars on the way out west, upon being asked by one of his henchman, "When are we going to eat the mice?" Cat R. Wahl replies, "Which would you rather have, the crouton or the entire Caesar salad?" Caesar salad was not invented until the 1920's and the movie takes place in the late 1800's.