"No, not counting you. I mean, you're already counted. Leo and Raph seemed pretty convinced that you're their Donatello, so that means you guys only count as two. I'm one. You guys are two. The kids were three, and this Casey Guy makes four."

Mike's logic is sound, it's just...he didn't really clarify that he was counting worlds, and not turtles. Mike seems completely unbothered by their talking at cross purposes.

"Right this second? No, I don't know where he is, but I know where he'll be. We're supposed to rendezvous back at the house whether we found you or not."