When Billy (Dacre Montgomery) gets the Byers address from Mrs. Wheeler (Cara Buono), he takes a cookie from the cookie jar on the kitchen counter. This was improvised by Dacre Montgomery, who said he thought it would be "cheeky."
When Steve (Joe Keery) and Nancy (Natalia Dyer) are looking through items from the shed, one of the things Steve picks up are the now-infamous Christmas lights from season 1.
At the beginning, Billy Hargrove (Dacre Montgomery) comes calling at the door looking for Max. Karen Wheeler (Cara Buono) finally answers, with husband Ted (Joe Chrest) asleep in front of the television. Billy and Karen then have a sexually charged, flirtatious moment as Billy asks after Max (Sadie Sink). Moments before, Karen was in the bath, reading a steamy romance novel. On the cover of the book are a man and woman locked in passionate embrace and who bear a striking resemblance to Billy and Karen.
Matt Duffer and Ross Duffer were nominated for the 2018 Emmy Award in the Outstanding Directing For A Drama Series category for Chapter Nine: The Gate (2017), but lost to Stephen Daldry for Paterfamilias (2017).
When Billy is at the Wheeler house looking for Max, he tells Mrs. Wheeler "I'm looking for my sister, Max...goes by 'Maxine'." This is the exact opposite of what is true. When she was introduced by Mr. Clarke at the beginning of the season, he introduced her as "Maxine" and she instantly corrected him, It's Max...Nobody calls me Maxine. It's Max." This was mostly done to show that Billy doesn't care to know her well as also evidenced by his constant retort that she is "not his sister".