On its way to Gun Hill, the train has four cars. By the time it reaches the station, there are only two, and the baggage car is a different one than before.
Near the end of the movie when Marshal Hogan leaves the hotel with Rick Belden, the sheriff is shown standing in a group wearing a dark hat, coat and tie. A few moments later he unties the horse and wagon that Hogan uses to go to the train station. Now he is wearing a tan hat and shirt.
The train that Morgan takes to Gun Hill is seen to go round the same corner twice, once at night and once during the day.
In the final scene at the train platform, Rick boards one car and watches Linda as she stands at the end of another car about forty feet behind his. As the train begins to roll, Linda runs toward Craig, who is lying where Rick dropped him on the platform, about forty feet ahead of his car. The next camera shot shows Linda leaning over Craig's body as Rick's car approaches her from behind. She could not have run that eighty or so feet faster than the train was moving.
When Linda changes clothes, a white strap suddenly appears then disappears on her left shoulder.
When Linda goes upstairs the second time with a rifle she doesn't ask for the key from her room. That should've been suspicious to the Belden's people sitting downstairs.
When Linda returns to the bar after having entered the hotel room to speak to the Marshal and see Rick, she wins the barroom bet by describing the new scar on the back of Rick's right cheek. However, she had only seen Rick from his front and left side, and could not have seen the now-healed scar.
Actor Brad Dexter ('Beero') delivers a theatrical left cross to Earl Holliman ('Rick Belden') who has been told by his father to fight Beero. But if you look closely, Brad Dexter accidentally punches the chair beside him.
When Matt Morgan is shot at in his hotel room from the outside, some telephone wires can be seen between wooden buildings. Not an anachronism as telephone wires are seen all around town and a wall mounted, hand crank telephone is seen in the sheriff's office.
Craig's voice is dubbed-over for two short lines when Matt is leaving the hotel with Rick, almost as if he used profanity and the censors wouldn't allow it. However, the words match the lips.