Maybe the most irritating thing about Roland Emmerich's generally unwatchable 10,000 BC was leading man Steven Strait's bizarre accent. Totally indeterminate -- he trilled his r's and drawled occasionally -- it was clearly meant to indicate in some uncertain way that what we're watching takes place a Very Long Time Ago. Hello? The movie is called 10,000 BC and the characters are already speaking English. Making them speak weird English isn't exactly adding verisimilitude. I don't know who Emmerich thought he was fooling.
I always find this sort of thing annoying, and sometimes vaguely insulting. I'm perfectly fine with characters who speak English even though they're not supposed to -- it's easier that way, and I can suspend disbelief. But if you're going to go that route, why add constant, pointless reminders of the very fact you're trying to dodge? Part of the reason I admire The Hunt for Red October is that John McTiernan said "screw it" and let Sean Connery keep his Scottish brogue as a Soviet submarine captain.*