
It suddenly occurred to me: the title 'Alvin and the Chipmunks' implies that Alvin (unlike Simon and Theodore) isn't actually a chipmunk. Otherwise it would be 'Alvin and the Other Chipmunks' or 'Alvin and Two More Chipmunks'.
But if he isn't a chipmunk, what is he? And aren't they all supposed to be siblings?