Factual error: The action in this movie takes place in 1869, yet half of the handguns are 1873 Colt Peacemakers, and the remainder that are Army or Navy Colts are all cartridge conversions, which were not available until 1871.
Factual error: As the stagecoach rolls into Prescott, Arizona, the road winds among hundreds of Saguaro cacti. Prescott is far beyond the northern limits of the Saguaro.
Continuity mistake: At the end of the town collapse, a sincerely drunk Ben dives head-on into a tub where a lady (in her underclothes?) is just enjoying a bath. Propelled by Ben's momentum the tub with both passengers slides down the slippery planks and splashes into the river, while Ben rearranges himself into a comfortable sitting position between shots. If I wasn't completely mistaken also the lady changes her outfit, since the embroidery is missing when they float along. (02:23:35)
Factual error: In the final gunfight, we see a close-up of Charley fanning the hammer and rapid-firing his six shot Colt Single Action Army nine times in a row. [Kostner has stated in interviews that this occurs because a short scene of him switching revolvers (he had a second revolver in his belt) was left on the cutting room floor. Still a mistake, but there's the reason.]
Audio problem: In the scene where Jack Bondurant is loading jars into the back of the truck, Floyd Banner is driven into town and screeches to a halt nearby. Although the tyres screech which is characteristic of tyres stopping suddenly/losing traction on Tarmac or cement, the car is on a loose dirt road.
Other mistake: During the car chase an Indian shoots an arrow that bounces off the car's license plate and comes back and hits the Indian. But a second before the arrow hits the Indian you can see him sitting on his horse with his eyes closed and a look of pain on his face as though the arrow had already hit him.
Revealing mistake: In the last scene, when Chris is leaving, it shows several shots of the peaceful village. Each time they show the village, in the middle of the square is what looks like two boys fighting. One punches the other and he falls down and gets up and punches back and he falls down. They do that about three times.
Other mistake: In the shot where the men are playing a game of baseball, if you look carefully in the background you will see that cars are driving down the highway. Considering that this movie was supposed to take place in the 1800's...
Other mistake: When they're roping the mustangs, the "stallion" doesn't have the genitals of a stallion.
Plot hole: Vic Gordon finds the Black Whip's clothes and puts them on. Then he goes to rescue Barbara Meredith (the real Black Whip). Strangely, her outfit fits him perfectly. In other scenes, he is taller and more muscular than she is. Did she keep several sets of clothes in various sizes, including boots?
Continuity mistake: As the girls ride in to town to avenge Kim, there is a deputy in a faded red shirt on a second-floor balcony. The first time he gets shot, he does a flip onto the street. The second time he gets shot, he goes over backwards.
Continuity mistake: Approximately 46 minutes into the film, Robert Preston is testing a new bullwhip. The whip is in his left hand as he brings his arm back and cracks the whip. He brings the left arm back for a second crack, and the shot changes to a closer angle just as he brings the whip down, only now it is suddenly in his right hand and not the left. The editing, the sound effect, the arm swing all seem perfectly coordinated, except that the whip changed hands between camera set-ups.
Factual error: When Jimmy Stewart is almost down to the runway during the bad weather, the aircraft exterior shots show the type of cloud tops found only at high altitude, not low to the ground.
Factual error: John Blair rides for the pony express, which operated until October, 1861. However, all of the handguns in the movie are cartridge Colts, which did not come into existence until 1871.
Other mistake: The objective of the band is a cache of gold hidden some years ago in the firebox of a wrecked locomotive in the wilds of Northern Mexico. When they finally dig the firebox door out and open it, the strongbox is sitting inside a completely clean firebox, with nary a cinder, ash, or chunk of burned wood in sight. If the loco and cars had been abandoned after the derailment, there would still have been residue in the firebox.