Dustin refers to the arcade game Dragon's Lair (1983) as "overpriced." Dragon's Lair was the first arcade game to charge $0.50 (even $1.00 in some markets) per play, breaking the $0.25 norm.
When Mr. Wheeler (Joe Chrest) asks Mike (Finn Wolfhard) if he'd jump off a cliff, Mike doesn't answer. In Season 1, Mike did jump off a cliff for a friend (albeit under threat from some bullies).
In an interview, Joe Keery (Steve) said that someone actually wrote Steve Harrington's fake college essay to use while filming the scene in Steve's car. He and Natalia Dyer (Nancy) couldn't stop cracking up because it was a "horrible, horrible, horrible essay."
When we first see Mad Max (Sadie Sink) skateboarding, she flips up her board, revealing a design that closely resembles the design of the Hoverboard from Back to the Future Part II (1989).
Sean Astin's involvement in this season reflects two other major points in his career. The four kids are reminiscent of the kids in The Goonies (1985), which was Astin's breakthrough role. He also appeared in the Lord of the Rings films. The books are referenced in the first season, with references to Mirkwood and Radagast.