Apparently they did consult a surgeon to find the most effective method of sewing three people together, which I guess is why they can slap the "100% medically accurate!!!" tagline on it. Really though, you could sew the people together hand to hand and it would still be 100% medically accurate, so it doesn't mean a whole lot...

Body horror, man. It's all just faeces and gurning.

ETA: And what are the odds of three random people being compatible anyway? Surely organ transplants go wrong all the time because of the body rejecting the new organ, so this... Why am I even thinking about it?