The first time that Oberyn Martell's nickname "the Red Viper" is mentioned onscreen.
Tyrion and Jaime discuss their cousin Orson, and Jaime comments there is no commonly accepted word for killing cousins. He refers to their cousin Alton Lannister, whom he killed in A Man Without Honor (2012) to escape captivity. In the books, they never discuss their cousins, and Jaime never kills a family member; the closest he comes is when his first cousin Cleos Frey helps him escape from the Stark forces, but is subsequently killed by outlaw archers on their way to King's Landing. Not only does Jaime not express any sadness over Cleos' death, he also strips him of his weapon and leaves the body for the crows and looters.
The episode won an Emmy Award for outstanding art direction for a single-camera series.
Sansa mentions Waymar Royce, Lord Royce's son, who was killed by a White Walker in the opening scene of Winter Is Coming (2011), thereby having the first on-screen death in the series.
In this episode, Littlefinger says to Robin that people "die at their dinner tables [...] in their beds [...] on their chamber pots". This is eerily prophetical, as the three major deaths that occur in King's Landing over the course of Season 4 - Joffrey, Shae and Tywin - take place at a dinner table, in a bed, and on a chamber pot respectively.