When Tom and Lucas are arm wrestling, Tom begins with a cigar in his mouth. The camera cuts away a few times to Mark, who is looking on, the last time the camera cuts back to Tom and Lucas, the cigar in Tom's mouth has disappeared.
When Richard Anderson meets up with one of his gang, there are no ashes or burned wood to indicate there was a campfire the night before.
In the opening scene, Mark is reading an almanac. It is a paperback book and has modern pages and binding. 19th century books were all hardcover.
The fire in the fireplace is propane.
When Richard Anderson meets up with one of his gang in the morning, Richard's right foot doesn't make it into the stirrup as they are riding away from camp.