When teaching Mel Gibson and Heath Ledger how to shoot a muzzle-loading rifle, technical advisor Mark Baker gave them the advice to "aim small, miss small", meaning that if you aim at a man and miss, you miss the man, while if you aim at a button (for instance) and miss, you still hit the man. Gibson liked this bit advice so much he incorporated it into the movie, just prior to the ambush scene.
In addition to Marion, Mel Gibson's character is also based on the life of South Carolina militia leader General Andrew Pickens. Pickens had his estate torched and lost a son before he went back into action and led the militia forces at Cowpens.
Among the American cavalry officers who participated in the real Battle of Cowpens was Lt. Col. William Washington - General George Washington's cousin, who went Mano-a-Mano with Banastre Tarleton in a saber clash.
After the explosion of the cargo ship we see (or hear, actually) Tavington smashes his glass when placing it down. He really just places it down, but it was decided to add a smashing sound for comic effect. We never actually see the glass breaking.
Screenwriter Robert Rodat called the final battle a hybrid between the Battle of Guilford Courthouse and the Battle of Cowpens: The mixture of militia and Continental army in the battle. The militia's reputation of not holding and the tactic of using that to lure the British in. The militia only firing a couple of volleys before a planned retreat to a secondary line composed of the Continental army. The Continental army firing and then performing a bayonet charge.
The Battle of Cowpens, upon which this movie is based, took place on January 17th, 1781. This battle has been commemorated by the U.S. Navy, which named two ships after it. USS Cowpens (CVL 25) was a WWII light aircraft carrier which won 12 battle stars, more than any other light carrier in the war and was the first ship to enter Tokyo Harbor and land Marines on the Japanese mainland. USS Cowpens (CG 63) is an Aegis Guided Missile Cruiser serving in the Pacific fleet from San Diego, CA.
The score used in the film is also used as the opening music in the 2004 television series Jack & Bobby (2004). Both featured Logan Lerman who played Benjamin Martin's youngest son William, and future president Robert (Bobby) McCallister.
The trivia item below may give away important plot points.
The character of Col. Tavington is loosely based on Col. Banastre Tarleton, who was Cornwallis's cavalry commander. Col. Tarelton had a bad reputation, but some say he was not nearly as cold-hearted and evil as the fictitious Col. Tavington (though many historians portray them equally). In the movie, Colonel Tavington died at the end of the Battle of Cowpens. The real Banastre Tarleton lived to grow old until 1833, became a general and even served in the British Parliament.