From London or NYC?

My niece was watching this and the Closed-Captioning was on. I noticed at the beginning the announcer says "Replacements are being flown in from London"... BUT the dogs had no British accent! They sounded like they were from NYC instead. Weren't any British voice actors available?

I DO like this movie. Just something I noticed. (Rowan Atkinson would have been PERFECT for the adult dog voice)