Film stock flipped when Lucky Legs and Sgt. Brock go into the tree house. The sniper has a left handed rifle, Sgt. Brock's knife is on the wrong side, and his watch has moved to his right wrist.
Throughout the movie both the French troops and the Viet Minh use American weaponry, such as the M3 'Grease gun', the M1 Carbine, and the Browning .50 cal machine gun. The French should be using the MAS-49 rifle and the Viet Minh either weapons captured from the French/Japanese or guns supplied by the Soviets.