Ahhhh. The Chicago Tribune "gets it."
Here's an English filmmaker (Minghella) directing an Australian (Kidman) and an Englishman (Law) in the leads, with an Irishman (Gleeson) and another Englishman (Winstone) in major supporting roles in an American Civil War tale filmed in Romania. Perhaps none of that should matter -- and some of these elements work just fine -- but the result is something that just doesn't feel authentic.
Historian Brian Pohanka comments on his role in the authenticity mission. (Skip to page two of this link to read his remarks - note that this link repeated below as "Gary Gallagher.")