It appears that Dodge City and Old Dodge Town are a night's ride from each other - see Trivia for this episode. But when Garth leaves to get Doc in Dodge, he gets back to Old Dodge the same day. When Matt leaves Dodge to go to Old Dodge during the day, he tells Newly that he should be back before dark.
When Matt is chained to the post and trying to get loose from the post to try to stop the hanging of Doc, the closeup scenes for the bolt and nut on the backside of the post has the length of the two about 1 inch. The view from the front side scenes shows inches of the bolt and nut on the backside of the post.