When Theon Greyjoy is shown standing on deck and smiling while making the crossing to Pike, the mole in shown on the actors right cheek, while in every other scene the mole is on the actors left cheek. The recorded image was flopped during the edits.
Valyrian steel is supposed to hold its razor sharp edge forever, without the need for honing. Yet during his conversation with Samwell, Jon Snow is seen doing exactly that with Longclaw, his Valyrian steel sword.
When Sam and the other rangers discuss things such as corpses farting, just before the end there's a shot over Sam's left shoulder. At the back of his fur coat can be seen the collar of a padded winter jacket sticking up with some sort of metal ring in it. When he says something about turnips and walks away, the collar's been tucked in.