Many movies have played with history and some of them made major mistakes. In my opinion, if you are going to do a history based movie do it right with the right facts and research. As a history student, I sometimes get really annoyed by the mistakes or changes that are made on purpose to either change the real facts, on the purpose to make one side look good and the other evil. Some movies are huge mistakes and destroy complitaly the concept and story, like Pearl Harbour (why oh why did they ruin what could have been a perfectly good movie with a love soap), U-571 and I would have said The Patriot, but the director said on numerous occasions that the movie was entirely fictional.
If you want good movies, with pretty good historical accuracy:
HBO mini-series Band of Brothers - incredible piece of work, great action, and on the long run you see the american soldies make a connection with the german soldiers and how they are all going trough the war
Joyeux Noel - Incredible movie...they have made changes to the real story, but this is an incredible piss of work. Set on christmas day in 1914, tells the tale on how German, French and Scot soldiers made peace for the night. Really shows how all sides suffered trough the war.
Der Untertag (Downfall) - Story about the last days of Hitler in his bunker told by one of his scretaries
There are some more that I really like, but those three are my favourites, and should be watched by everyone. They are all well acclaimed productions and pretty easy to find. Why these movies are good in my opinion, is that they go a bit further and look back at history from all sides. OK, Band Of Brothers is a typical american WW2 series, but even there, with all the inputs from the veterans, the Germans are (well in some parts they are) not downgraded as some other movies do (
http://www.youtube.com/watch?v=Ds85Zko0cT0 probably one of the best scenes).
p.s. how do add youtube clips on this new format?