I agree with both, though I diagnosed point #1 as "unintentionally intentional" — insofar as a dialect coach would have cleaned up the accent of a genius actor like Tim Roth in 10 seconds flat. I'll check the bad southern accent to be part of the whole gag of his assumed identity.

I need some recco's for more movies like this, and it sounds from Matthew's comment like I've found a connoisseur?