The episode title refers to the rebellion of the North under their new King Robb Stark, in response to the execution of his father Eddard Stark. The phrase is also used prominently in the novels, mostly in the context of a warning that the people of the North will get even with the Lannisters and their allies for all their atrocities.
In the novels, it is made explicitly clear that the Hound, Sandor Clegane, hates liars. When Sansa tries to lie her way out of her blunder with Joffrey in the opening scene, Sandor steps in and backs her up - in other words, he became a liar to save her from a beating.
According to the novel, only one of Robert's bastards was killed by Cersei's command - baby Barra. It was not Janos Slynt, but one of the Gold Cloaks named Allar Deem who killed her and her mother who tried to stop him.
According to the novels, Davos' left fingers are cut at the first joint, as result of the punishment Stannis gave him for breaking the law for years. In the show, it was changed from Davos' left hand to his right, because the actor Liam Cunningham is left-handed.
Despite their same disgust for Joffrey, in the novels, Tyrion and The Hound have a notorious hatred for each other. This relationship is alluded to when Tyrion points to Sandor and says, "This one doesn't like me much." The novels never reveal what happened to make them hate each other.
During the scene in which the idols of the Seven are burnt, Selyse Baratheon (Stannis' wife) is standing among the crowd. She is played by Sarah Mac Keever, but without dialogue or on-screen identification.