Throughout the chase/escape segment where the Hurricane Express, carrying a shipment of gold, is to be wrecked and robbed; the plane used to remove the Wrecker from the train, bring the Wrecker to his gang, chase the train to get the gold after Larry stops the wreck, and a couple of other scenes; continually changes from a single engine bi-plane to a dual engine monoplane.
In Chapter 12 when Larry (John Wayne) carries a unconscious Frank Stratton (Edmund Breese) and puts him into their car. Larry then drives off to catch the Wrecker that is getting away in the Hurricane Express. Catching up to the train, Larry jumps from the car onto the train engine. What became of Stratton? He's no longer in the car.