While other folks are in the weeds about British uniforms, I can tell you that the movie switched several things around from JFC's book, to include Cora being the "love interest" and surviving, while her sister dies instead. Since Colonel Munro was fictional, his heart could be cut out--or not, depending on the need to feature blood and drama. As to whether the colonial militia could up and leave, yes, they could. And many did.

I can say with conviction that I found the movie infinitely better than the book. JFC wrote like his pen was stuck in molasses, and he never met a dependent clause he didn't love.

Daniel Day-Lewis is an exceptional actor because he can do American accents effortlessly.