When Farrell climbs out of the stage he has both guns holstered, but when he takes over the reins his right holster is empty. In the next shot the gun is back in its holster.
When Sheriff Harris sits down at his desk upon meeting Steve Farrell, he lights his cigar and extinguishes the match twice between shots.
The firearm in the title and in use in the movie isn't a Colt .45. Colt never made an open-top revolver in .45 caliber, as it was too much gun for that configuration. The biggest it could be is a .44, like the Dragoon or Walker. The .45 caliber didn't show up until Colt made his Single Action Army model.
The fire pit in the tepee appears to be made from brick and mortar. Indians who used tepees were nomadic in nature. A permanent fire pit as that shown in the movie would not have been implemented by nomadic Indian tribes.
When Beth Donovan cuts her way out of the tepee it is very clear that that she is cutting thin cloth and not the buffalo hide from which tepees were made.
The inside of the tepee shows perfectly straight creases as though is has been folded up in a rectangular fashion.
When the arrow is shot into the sheriff's office door, the point initially sticks through just enough to see it and then after a second or two it is clearly shoved through a little harder so that the arrowhead protrudes most of the way through the door.
At the end of the film when Steve Farrell walks up to Beth Donovan, he is holding one revolver. Yet seconds later, he is seen holding two.
When Steve makes his break from being arrested, a man jumps up on the back of a wagon and draws his gun. There is already a black spot on his shirt exactly where the arrow hits him.
The movie is set in 1851 yet when the lights are knocked out in the Sheriff's office they clearly are electric (the last one even hangs from the wall by its electric wire after being knocked out). Electric lights weren't invented until approximately 1880 and electricity to such a town would have been lucky by 1910. Also costuming reflects 1870s, not 1850's, styles and fashions.
At about the 16 minute mark Farrell yells "Hey!", but Randolph Scott appears not to have yelled anything.
(at around 1 min) There is a shadow of a crew member with headphones, upper left above the doorway as Randolph Scott approaches.