User blog comment:DementedP/Isayama's take on Episode 23/@comment-7418318-20130915184302/@comment-179280-20130915193051

Ugh. I really disliked that laughter. Although admitely, it looked sexy, and that's why I disliked it. I don't think she wasn't supposed to look sexy at all...

That aside, what I could gather from the text (I'm by no means expert at reading japanese) is that Isayama wanted Annie to show a bit more of emotions at the moment of being confronted, that's why he drew a rough draft with Annie trying to "contain her tears" or "blushing and laughing". The anime director seemed to like the later, but on Isayama's intention was that Annie had to express some fear, sadness, embarrasement, guilt, loneliness, and a sense of openness. He also mentions that he feels that it gives a clearer message that Annie was showing that although she's a monster, she did what she had to, and that he wanted her to show more "human feelings" (although I doubt I will ever like the change lol).

On what I can interpret, Isayama seemed to like the change, and call me a dreamer, but that may hint at future character development for Annie in the manga.