- Gendry's weapon of choice, a warhammer, is the same as his father Robert Baratheon used to kill Rhaegar Targaryan, Jon Snow's real father.
- Capturing a wight was attempted back in Season 1, which Joer Mormont sent to Joffrey as a proof.
- Gilly reveals that Jon Snow is not a bastard after all, and may be the rightful heir to the Iron Throne.
- Gendry and Jon greet each other like their fathers did, commenting on each other's appearances.
- Sam's father snarked at him back in Season 6 that he's "spending his life reading about achievements of better men".
- Cersei forced Sansa to write that note back in Season 1.
Part of course:
Details you may have missed in Season 7 Episode 5