1. The title screen during the opening credits decays a little every season.
2. There's a creepy face in a tree during the first episode.
3. Edwin Jenner's warning to Rick in the Season 1 finale is the title of the Season 7 premiere episode, in which Rick and his group meet Negan and reach their low point.
4. What Merle says while stuck on the roof is the same as what he says right before the Governor kills him.
5. There's a Spam knockoff called "SMEAT."
6. The Governor stumbles across a beheaded corpse with a sign nailed to it that reads "LIAR." In the next episode he says nothing but the word "liar" immediately before beheading Hershel.