Revealing mistake: At the beginning of the episode, Robb and Blackfish Tully are pushing Hoster Tully's funeral boat down the river. When they climb back onto the dock, there is already a trail of water going from the steps and ending where Robb ends up standing. None of the other characters standing on this portion of the dock have wet clothes, meaning none of them went into the river, indicating that the trail of water was from previous takes.
And Now His Watch Is Ended - S3-E4
Revealing mistake: When Karl kills Craster, you can see the blood packet in Craster's mouth right before he spits up blood.
Suggested correction: It's not a blood pack. It's Karl's blade.
Phaneron ★