Via The Economist's Johnson blog comes this entertaining video of the young stars of the "Harry Potter" movie franchise trying to sound American.
As pointed out by the Johnson blogger (Lane Greene), Rupert Grint goes overboard with his pronunciation of "mozzarella sticks" as "mozzareller sticks." That's a hyper-rhotic extension of "intrusive /r/," since the inserted /r/ is followed by a consonant rather than a vowel as in "law[r] and order" or "draw[r]ing." This over-/r/-fulness, what Ben Sadock calls "intrusive intrusive /r/," is frequently heard when non-rhotics try to go rhotic. For more on hyper-rhoticity and how it plagues British attempts at imitating American accents, see my Language Log post from 2008, "Botswaner and Louisianer."