A machine gun nest ambushes charging Mexicans by cutting down the first three over a wall with a short burst, but as hordes more come over the wall, the machine gun doesn't fire even though the sounds of it firing continue. The gun obviously jammed but the footage was used anyhow with firing sounds dubbed into it.
In the first flight with Arnold & Fierro, they observe the train approaching a causeway over a valley at speed. They return to Chupadero to report to Villa. The next day, they fly over the train again, which is a few feet past where they saw it before crossing the same valley.