It may sound a bit silly, but in X-Ray mode you can see Hange's anus completely, and in the 3rd arc we deal with this hole the most, Annie's is seen less and if I'm not mistaken there is not mostly anal sex with Annie, and Mikasa's is only seen pussy. It only seems to me that from the very beginning they were hinting at us what to expect from this part of the arc

. I last played right after 0.27.1 came out and I may not remember well, correct me if I'm wrong, or write if you think "it's" possible or not.