The joints (is that the right word?) on her face make her look kinda like a duck, but she is a damn fine looking robot midget horse.
Wait, if robots in FiW are covered in artificial skin that makes them superficially indistinguishable from ponies, why is she obviously a robot? Has she somehow gained a soul and is now recognized by the powers that be as an honorary biological life form?
I think you'd have to ask the FiW guys for the answer to those questions heh. ^^ But then, if we continue your train of thought, why doesn't anyone react to her voice or the sounds she makes when moving around?