When Frank approaches the two boys by the church, a modern high tension steel power line tower can be seen at the top of the hill between that church and the building on the left. A later closing shot reveals this hydro tower again for about five seconds.
Near the beginning: As The Virginian is driving a wagon into Medicine Bow, there is what appears to be a modern railroad train approaching from the left about half-way up the side of the mountain above the Medicine Bow railroad station (just above the station's smokestack). After a short change in shot, the train is visible again briefly when The Virginian is on-screen.