It's only on screen for a matter of a second or so in the trailer, but there's a very brief flash of the treacherous Alliser Thorne and fellow Night's Watch members attempting to break down a door. Presumably Jon Snow's body lies behind it as well as those who remain loyal to him. So the Mutiny at Castle Black clearly doesn't end with Snow's murder: is Thorne now leading an attack to kill Ser Davos and Melisandre? Hopefully he will finally get what he has coming to him.