When Theon is standing on deck while crossing to the Pyke, there is a mole on his right cheek, but in every other scene - the mole is on his left cheek. The recorded image was flipped during the edits.
Balon claims that Ned Stark killed Theon's brothers, Rodrik and Maron. Ned did not kill either of them: Rodrik was killed by Jason Mallister at the battle of Seagard, while Maron was killed by a collapsing tower during the Siege of Pyke.
When Sam and others discuss corpses farting, the collar of Sam's fur is sticking up. When Sam says something about turnips and walks away, the collar has been tucked in.
When Yara is giving Theon a lift on horseback, the actress galloping along the beach is clearly a stunt double and not Gemma Whelan.
Valyrian steel is supposed to hold its razor sharp edge forever, without the need for honing. Yet Jon is seen doing exactly that with Longclaw, his Valyrian steel sword.