Rocket should've been cockney or Scottish - simple as that. When Bradley Cooper was cast as the mercenary raccoon in Guardians of the Galaxy - after the likes of David Tennant had been linked to the role (we think Billy Connolly would have been ideal, but that's another matter) - it was actually something of a disappointment. Those who read the comic books generally perceive Rocket as cockney or Scottish - British, either way, at least - and it should really have been the same in the movie. That said, Cooper did a decent job in the end, so we're really just nitpicking here.
