Tom Hopper replaces Freddie Stroma as Dickon Tarly, the second son and heir of Randyll, and younger brother of Sam. Stroma was unavailable due to scheduling conflicts. Jaime mistaking Dickon for "Rickard" (a more common name in Westeros) is a winking acknowledgment to the audience that the character is now played by another actor.
In this episode, Archmaester Ebrose (Jim Broadbent) breaks the bad news that Jorah can't be cured, making his death by the disease seem inevitable. So Jorah writes a letter to Daenerys: "Khaleesi, I came to the Citadel in the last hope that the maesters could treat me, as you ordered. Even with all their arts, I am beyond any cure but the grave. I have had a longer life than I deserved, and I only wish I could've lived to see the world you're going to build, standing by your side. I have loved you since the moment I met you."
The Shivering Sea, a frigid sea that borders northern Essos and eastern Westeros, appears in the opening credits near the Wall. This builds off of a line from the previous episode where the Sandor "the Hound" Clegane, when looking into the flames, says he sees a vision of a place where "the waves are frozen".
Tyrion's strategy and rationale to capture Casterly Rock, in order to weaken Cersei and Jaime's position and show the Lords of Westeros that they are not invincible, is almost identical to the plan devised by Robb Stark in The Rains of Castamere (2013), which was never executed due to the Red Wedding. It only happened on the show, as in the novels, Robb planned to abandon his conquest of the Riverlands and return to the North, to drive away the Ironborn.
The first appearance of the dragon skulls since Arya found them in The Wolf and the Lion (2011). The skull of Balerion appears to have been enlarged slightly from its earlier appearance, probably to match Joffrey's assessment from The Bear and the Maiden Fair (2013) that it was the size of a carriage (the novels describe Balerion swallowing a war-horse and its rider whole with ease). It was created in six weeks as a full size, 30 feet long, 11 feet high and 16 feet wide polystyrene model; a real sheep's skull was studied for surface texture.