When Catelyn talks to Lysa, the shadows keep changing dramatically. When shot from behind Catelyn, there is one strong shadow behind her and Tyrion. But when they change angle (just after Lysa's son says, "Is that a bad man?"), the shadows are suddenly vague and in the opposite direction.
Maester Luwin tells Bran that his mother had sat by his bed for three weeks while he was unconscious. In The Kingsroad (2011), Catelyn tells Robb that she had prayed for Bran to the Seven for more than a month.
In the scene when Maester Luwin is quizzing Bran on the noble houses and their words, the 2-person pan shot shows Bran with bangs, but when it zooms to him, his hair is split in the middle.
When Maester Luwin is doing lessons with Bran, while Luwin is discussing how Bran's mother loves him, Bran is playing with a silver figure. He is using the sharp end to carve into the table, yet when the shot changes he is holding it in a different position in his hand with the dull end of the figure to the table.
When Sandor "the Hound" Clegane rushes to protect Loras Tyrell from Gregor "the Mountain" Clegane, his sword appears in his hands without drawing it.
After overhearing a conversation, Arya is pulling at the padlock. It makes no sense, because the bars of the gate are spaced far enough for her to easily squeeze through.
In the fight between Jaime and Ned, they are fighting in the open, but you can see multiple shadows.