I said it earlier but I think people saw it and they left it assuming no one beyond sharp eyed fans would notice or care. I guess they didn't realize that the world is such a Shangri-La that people have nothing more to worry about than a cup seen for a few seconds on a TV show.There is no way no one saw it. Forget the post production, color timing and all that. We could say someone missed it on a 2D TV image. But there is no way that no one in person on the set did not see it. It is not possible to have a cup on the table that close and not see it. The first person, Emilia Clarke should have seen it. Especially that the table is relatively empty.