For starters, to play a German officer. Shouldnt you be able to speak with a German accent?
Kinda adds to the credibility.
Either go with the German language and subtitle it, or use plain English. In this case, going with the latter is fine with me. What I never find credible is Germans speaking to each other in English with German accents, and, like you see in many other films, Russians speaking to each other in English with British accents.
Tom Cruise may be a tool, but a lot of the posts here show ignorance of the history surrounding this event. Even the History channel approaches the topic with more subtlety than what I'm reading here.
Fact is the German High Command was full of selfish opportunists. Had their little master race plan worked they'd still be goose stepping around the world. Call it what it is.
The upper echelons of the German military were made up of Prussian conservatives who had nothing to do with the origins of Nazism (and nearly all thought his plans for conquest were outrageously presumptuous). They resented Hitler as a plebian, but after Hitler quashed the storm troopers, who were scheming for control of the military, it was difficult to plot against him because he seemed to be preserving the old conservative order.
