Waterloo (1970)

Revealing mistake: The cannons shown are firing blank charges, which produce no recoil. Recoil has been simulated by towing the guns backwards when they fire. The problem is, there is always a distinct delay between the discharge and the "recoil".

Revealing mistake: During the battle, both the Allied and French commands spot unknown troops marching towards the battlefield. They are marching through what looks like a wheatfield, following paths which have already been made. However, these new troops are marching on a route so far unused by either the French or Allied armies, so therefore the field should have been untouched - these paths were made on the first take.