Factual error: As Sgt. Saunders and his squad dodge artillery fire in the ruined city, modern high-tension electrical towers are shown. Also, no electrical towers whatsoever would have survived a prolonged artillery bombardment without being damaged or destroyed.
Actor Vic Morrow used a non-firing wooden replica of a Tompson submachine gun due to its lighter weight, thus being easier to carry. He used a heavier blank-firing model when it was required to be fired.