I did miss several bits of it as I was trying to be productive and not stay on the couch all day, but I noticed that there were many actors from the UK pulling convincing American accents in the film- many actors I've enjoyed in other pieces.
Damian Lewis is fantastic as Captain Winters, one of the main protagonists of the piece.
James Macavoy plays a fresh faced replacement, Pvt. Miller.
Marc Warren plays the very sympathetic Albert Blithe.
Andrew Scott plays Pvt. "Cowboy" Hall. Look at that pout. His voice is deeper for this role than the voice he used in Sherlock and My Life In Film as well.
Tom Hardy from series such as Wuthering Heights and Oliver Twist plays Pfc. Janovec
Michael Fassbender plays yet another soldierly role (previously from 300 and Inglorious Basterds) plays "Pat" Christenson.
Simon Pegg does a great American accent as Sgt. Evans - great Scottish as well in Star Trek.