1. The creators of the series, The Duffer Brothers, were major fans of old school horror flicks and incorporated numerous 80s movie references throughout the series.
2. Some of the movies referenced include The Goonies, Close Encounters, Stand By Me, Jaws, It, Evil Dead, The Thing, Poltergeist, ET, Carrie, Star Wars, Alien, and Halloween.
3. 906 boys and 307 girls were auditioned for the lead roles.
4. Millie Brown (Eleven), Finn Wolfhard (Mike), Gaten Matarazzo (Dustin), Caleb McLaughlin (Lucas), and Noah Schnapp (Will) were ultimately selected as the bad ass lead characters and all of them are under the age of 13.
5. Millie Brown was really nervous about shaving her head and was encouraged to think of Charlize Theron in Mad Max to inspire the drastic change.
6. Her character noticeably didn’t have many lines; most of her phenomenal and creepy performance being entirely based on her facial features. For that, the Duffer Brothers asked her to model her performance after the character of E.T.
7. Millie and Charlie Heaton (Jonathan) are both from the UK.
8. Millie learned how to do an American accent by watching Disney Channel movies while she was growing up.
9. All of the young leads were asked to watch Stand By Me, The Goonies, and Poltergeist.
10. They did actually use 1200 pounds of Epsom salt to get Eleven to float in the pool.
11. Originally, Steve and Nancy were not supposed to end up together at the end of the season. Joe Keery, who played Steve, was reportedly so likable and charming on the set that the show runners changed his character arc so he could be included in more episodes.
12. A spokesperson for the U.S. Department of Energy actually reviewed the series and while he denies that the DOE explores anything like a parallel universe, the DOE does fund a lot of research towards maintaining the Large Hadron Collider—which is the largest and most powerful energy device on Earth.
13. So while the DOE may not be delving into alternate dimensions, they do fund a significant portion of space explorations.
14. Gaten Matarazzo’s (Dustin) voice changed so dramatically during production that the post-production sound team was unable to use him for any of the additional dialogue after filming.
15. Gaten and his co-star Caleb McLaughlin (Lucas) knew each other prior to filming. They both performed on Broadway—Gaten played Gavroche in Les Miserables and Caleb played Young Simba in The Lion King.
16. It was at Caleb’s request that his character Lucas wear a camouflage bandana in the show—which he wears in the final three episodes.
17. Winona Ryder wanted her hair to be modeled after Meryl Streep’s in Silkwood.
18. Ryder also took a lot from performances from Alice Doesn’t Live Here Anymore, Max Dugan Returns, and Audrey Rose—all movies that feature a female character who struggles to tell the truth despite everyone else thinking she’s insane.
19. The monster was created with prosthetics, animatronics, and CGI.
20. The toddles on set (a set of twins shared the role of Mike’s little sister, Holly) were so terrified of the monster that the staff had to tell them that the monster was just like the monsters in Monsters, Inc.
21. Hopper’s trailer apparently cost the art department $1 to buy.
22. For the laboratory scenes when Eleven is in the immersion tank, Millie wore a Sea Trek helmet, which weighs 70lbs above water and 15lbs under water.
23. And to direct Millie while she was underwater, the directors communicated to her through a small radio in her ear.
24. The soundtrack is all 80s music—with significant emphasis on The Clash’s “Should I Stay Or Should I Go.”