When Harley was beaten the first time in the bar, he was stabbed a number of times in the stomach and chest. When he gets beaten at the bar the second time, as he is dragged out his shirt rides up showing no knife wounds.
When the fight scene between Duke and Roy spills outside, Roy is suddenly wearing a black t-shirt under his sweater.
The army base that the tank is stolen from has no live guards and just has a chain link fence that the break into with a bolt cutter. That would never be the scenario on a US base.
During the climatic fight between Duke and Roy, Thalmus Rasulula's stunt double is visible several times.