The real Robert Rogers authored a set of rules of warfare known as '28 Rules of Ranging' which, in one form or another, has been used by various units of the United States Army, including the 75th Ranger Regiment, to this day.
The real John Simcoe was actually a beloved figure in Canada accomplishing many charitable civic acts, and was a staunch abolitionist, likely not at all the villainous sociopath as he was portrayed in the show. He actually did lead the Queen's York Rangers in the war, and went on to found the city of York which would later become Toronto.
Benedict Arnold, while the son of an alcoholic, was also raised in a wealthy household and became a very successful businessman in his own right starting with an apothecary shop. He only changed sides in the war when he had already given his all for the Colonial side and was being mistreated and ignored. He beggared himself to equip his troops and requested compensation and recognition, which was not forthcoming. Washington himself continually neglected his most accomplished general, passing him over for promotion in favor of those less-deserving and promising re-payment time and time again, to no avail.
This show is the second time Kevin McNally has portrayed a man in the American Revolution. The first time was in Assassin's Creed III(2012) as a sailor named Robert Faulkner who aided the main protagonist in naval battles. This also makes it the third time he has portrayed someone from the 18th century. The first of three being Gibbs in the Pirates of the Caribbean movies.