During the battle at the Tower of Joy, Arthur Dayne fights the remaining four Stark men with both his swords covered in blood. At this point in the battle, he had only struck one man with one sword.
On Two Swords (2014), according to Gerold Hightower's entry in the Book of Brothers, he was present at the Tower of Joy with Arthur Dayne and Oswell Whent, and died there. In this episode, only Arthur Dayne and Oswell Whent are present at that scene.
The cloth covering Jon in the closing scene of the former episode miraculously disappears before the opening scene of this episode.
When Arthur Dayne approaches Ned Stark, he plants one of his swords in the ground in front of him. After a short speech, he draws both swords and begins fighting, and there is no sword in front of him.
After the execution, Olly's head (which they close-up on seconds before) has now changed positions considerably.
Eddison Tollett tells Jon "Your eyes are still brown." Jon's eyes are gray.
When Tyrion talks with Grey Worm and Missandei, his glass shows different amount of liquor in it during different scene cuts. The amount of liquor changes every time the camera angle changes.
(6:20) At the beginning, as Jon comes down from the stairs, a horse can be seen on the far right that does not move an inch. You can see it to the right of the horse that is moving. The (probably) prop horse is even in mid-step.
Othell Yarwyck says that his mother lives in the White Harbor. However, the White Harbor is located in the North, while the seat of House Yarwyck is in the Westerlands.