Referee made a mistake but recommended acceptance, what to do? I recently received a referee report on a math paper in a mid-tier journal.

In this paper I proved (to give an example avoiding technicalities) that all dogs are cute.
But the referee claimed in his report that I claimed that all animals are cute (that is, he claimed that I proved something much stronger than what I really proved).

There is no way to understand the more general statement from my paper, and my guess is that the referee simply did not read the paper carefuly.

Now, the referee recommended acceptance, and the editor accepted his recommendation. 

Should I do something about it? should I explain this to the editor?
I would probably mention it, but not make a big deal out of it.  The referee here was lazy (by not reading carefully), the editor was lazy (by not looking at the main result of the paper), so my plan would be to be lazy too.  I'd write an email back with the final revisions and mention casually in the text of the email "just to correct the record the referee wrote animals, but they must have meant dogs which is what's actually in the paper."  Odds are the editor won't read your email carefully and won't even notice your comment, but you'll feel better.

Peer review is such a random crapshoot anyway, and you obviously thought this journal was appropriate, so there's very little actual harm here.  You can be sure that at some point the same thing will happen in the opposite direction and you'll have a paper unfairly rejected by a referee who didn't bother to read the main result and the editor almost certainly won't do anything to correct the error.