Hollywood Tactics: Lord Cornwallis, did you ever learn that you DON'T fire cannons into the center of your army unless you want to hit them too? Remarkable though, this is Truth in Television because there were occasions where Cornwallis really did fire cannons into his own troops in order to hit the Americans.
The whole final battle in general, which was a mix between the Battle of Cowpens, and the Battle of Guilford Courthouse (The latter one the British actually won, though it was a Pyrrhic Victory!). It is very very difficult to hide a reserve army of app. 10.000 men only 500 meters away from the enemy behind a small hill. It was impossible for Cornwallis not to notice it. Although the Battle of Cowpens did have a forward line of Militia luring the British into charging headlong into the better-trained regulars hiding behind a dip in the terrain. The circumstances of the Battle of Cowpens and the battle in the movie were rather different.
It's not just the circumstances, but the actual tactics and progression of the battle. At Cowpens Daniel Morgan placed three lines: a line of sharpshooters, which fell back to join a line of militia, which fired two volleys and retreated further to join a third line consisting of Continental regular infantry. Who were standing on a hill. In plain sight. The three initial lines of battle weren't so much there to trick the British, but to wear them down. The actual trick was that behind said hill was waiting a detachment of cavalry under William Washington, (and yes, there is a relation) who sortied against the British right flank and rear while they were engaged with the regulars. And while this was happening, the militia from the first two lines circled around behind said hill, reformed out of view of the British, and then counter-charged on the left flank of the British line to complete a double-envelopment of Tarleton's army.
This example needs to be revised:
It starts off by complaining about unrealistic tactics, then noting they are in fact Truth in Television and gets more nattery from there.
You've got roaming bands of armed, aggressive, tyrannical plumbers coming to your door, saying "Use our service, or else!"