Haha. Looks a bit mad innit? A bit like the Superman cover, "funny looking". I'm thinking it looks funny because it's meant as such.
Btw Miller drawing anatomy that doesn't match up isn't something new.
Here's a pin up he did for Judge Dredd. Meant for a cover (which went unused).
Miller is not on art duty in TDKIII other than the Atom mini comic (which btw looks really good) as of yet. No worries