Executive Producer Tom Luse says that slaughtering the POW's inspired Rick to read Carl's letter. "He realizes that violence for violence's sake is not enough so he reaches out to Carl for guidance."
Jadis's walker cart was built so the handle could fold down. This means the walkers face could have been folded down on top of Negan.
Joshua Mikel (Jared) was a Walker in the Season 2 finale "Beside The Dying Fire."
This is the third time a Helicopter is seen flying in the show.