The second time Josh goes to the fort, he makes a half-hearted attempt to tie his horse to a railing and the reins end up loosely hanging over the railing. A couple minutes later, the reins are securely tied.
Josh rides into the fort and calls out to Col. Sykes. As he's riding away from the camera, a vehicle's tire tracks can be seen behind the horse.
About 1 min. 40 sec. you can see tire tracks on the ground when Randall arrives at the fort.
When Josh goes to another town to talk to a printer about the fake wanted poster, he ties his horse to a railing, and as he walks away, a shadow of the boom mic is seen on the ground, following him.