Aside from the obvious historical misdirection, the activity in this movie takes place in 1941. This period would be indicative of the activities of the Royal Navy against the German Navy, but not the U. S. Navy. While the captured German submarine is of the right period, a Class 7, I hope the producers used a model of a 'S' Class submarine rather than the more ubiquitous Gato or Guppy Classes of submarines.
While I do not know enough about U-571 to attest to the historical authenticity of the uniforms, equipment, and dialog, I can say that in THE PATRIOT's case here is an example of where excellent advice was provided and not considered. Mr. Emmerich, excuse me sir, but it would not be that much more expensive to use the advice of the Smithsonian and others and make the film with authentic weapons and uniforms. Geez.
Between you and me, I have this feeling that the prodco will certainly have enough budget to make sure Ms. Lisa Brenner's hair is just so. It's enough to make you wanna cry.
Both of these movies are previewed in Upcomingmovies.com. http://www.upcomingmovies.com/ .