Grab your Eggos and don't let go because we're finally heading back to the Upside Down. 

Created by brothers Matt and Ross Duffer, Stranger Things came out in 2016 and quickly became a pop culture sensation as viewers were unable to resist the nostalgic adventures, fierce friendships and monster mysteries that were going down in Hawkins, Ind. Its young cast—Millie Bobby Brown, Finn Wolfhard, Gaten Matarazzo, Caleb McLaughlin and Noah Schnapp—were overnight sensations, David Harbour became a sex symbol and Winona Ryder staged a major comeback.

Now, six years, four seasons and a lot of bad hairstyles in, fans are preparing to say goodbye to Eleven, Mike, Chief Hopper and the rest of the gang. And Netflix confirmed that production on the fifth and final season of Stranger Things is underway by sharing a sweet group photo of the Hawkins crew back on set.

"THIS IS A CODE RED," the streaming service announced in an Instagram post Jan. 8. "STRANGER THINGS 5 production has officially begun!!!"

The black-and-white photo showed all the returning cast members reuniting ahead of the final season, including the seven OG cast members, the Duffer brothers and Sadie Sink, Joe Keery, Charlie Heaton, Brett Gelman, Maya Hawke, Natalia Dyer, Jamie Campbell Bower and Priah Ferguson.

While the final installment was initially slated to begin filming last May, the Writers Guild of America and, ultimately, the SAG-AFTRA strike shuttered production for months.

But did you know that the show almost never made it to air, with many networks turning down the Duffer brothers' homage to the movies they loved in the 1980s? And you thought the Mind Flayer and Vecna were evil.

Check out all these fun facts you might not know about Stranger Things, including the show's original title, the two beloved characters who were supposed to die in season one and the actor who filmed himself dancing in a G-string to land his role. Hey, stranger things have happened...

1. After working on M. Night Shyamalan's Fox series Wayward Pines, brother writing duo Matt and Ross Duffer came up with the concept for Stranger Things, though it was initially called Montauk. 

"It's very hard when your brain is latched onto a title, it's really, really hard to get people to agree and accept another title," Matt Duffer told The Daily Beast in 2016. "Initially when we came up with this title Stranger Things, it was hard for people to embrace. It's actually taken like a full year for people to get used to it."

2. The Duffers envisioned filming the series on Long Island, but their top choice for location ultimately proved to be too challenging. 

"We liked Montauk, because we liked the coastal setting, and Montauk was the basis for Amity, and Jaws is probably our favorite movie, so I thought that that would be really cool," Matt Duffer explained to The Hollywood Reporter. "Then it was really going to be impossible to shoot in or around Long Island in the wintertime. It was just going to be miserable and expensive." Atlanta ultimately became the home base for production.

3. Before Netflix picked up the series, almost 20 other networks passed on the project, according to Vulture, with executives believing audiences would not be able to invest in a show starring four children. 

4. To play Eleven—a child who escapes from the confines of a facility where she's being subjected to traumatizing tests that have infused her with telekinetic powers—a then 12-year-old Millie Bobby Brown had to say goodbye to her hair.

"The day I shaved my head was the most empowering moment of my whole life," Brown reflected during PaleyFest in 2018. "The last strand of hair cut off was the moment my whole face was on show and I couldn't hide behind my hair like I used to. As I looked in the mirror I realized I had one job to do: inspire...Shaving your head is so empowering. You don't need hair to be beautiful. You are beautiful with or without. I learnt that too."

5. The actress told E! News in 2016 that she drew inspiration from Charlize Theron in Mad Max: Fury Road, as well as one of her co-star Winona Ryder's old yearbook photos.

"I showed you my school picture!" Ryder said to Brown when her buzz-cut came up, with Brown saying, "Winona looked cool back in the day with the pixie cut and I thought maybe I could bring it back!"

6. The British star later revealed she turned to a surprising source to perfect her American accent: Miley Cyrus' Disney Channel series Hannah Montana. "It's so good. Hannah Montana is the best," Brown told Jimmy Fallon during a recent visit to The Tonight Show. "Like the film, everything. Everything about it is amazing. And I got the American accent."

7. To find their four main kids, the Duffer brothers had the young actors audition with scenes from Stand By Me. 

8. When it came to finding their Mike, the Duffer brothers had a different idea for the character before Finn Wolfhard auditioned. 

"Originally Mike was a sigher, he was a dreamer, he was much more like Mikey in The Goonies in a lot of ways," Matt told The Daily Beast in 2016. "But Finn had this really anxious, twitchy energy about him and we thought that that was really great and we just kind of wrote the character to match him and his personality."

9. Another actor who influenced his character was Gaten Matarazzo as Dustin, with Matt explaining, "I don't think we really understood who that character was. He started out more like a stereotypical nerd and then we met Gaten and we basically tailored the show to him."

10.Thanks to Eleven's affinity for Eggo waffles, Kellogg's saw a significant increase in sales after they were featured on the show. The company said consumption was up 14 percent in late 2017 after season two was released and October saw the most mentions of the product on social media in a single month.

11. In early 2018, Harbour went viral when he fulfilled a fan's request to take her senior portraits with her after she tweeted at him, "How many retweets for you take my senior photos with me." Harbour replied, "25k. And I get to wear the school sweatshirt and hold a trombone." The actor held true to his word, even holding the instrument in the photos.

"Voted most likely to hijack someone's high school senior photos 24 years later," Harbour wrote on Instagram. 

12. Later that same year, Harbour was once again up to his social media shenanigans, this time officiating a viewer's wedding in exchange for 125,000 retweets and the first slice of cake. Harbour got ordained and performed her marriage ceremony dressed as Chief Hopper.

13. Many fans theorized early on that Eleven could be Hopper's daughter, though he eventually became her surrogate father. And in a sweet Easter egg, Eleven is seen wearing the blue braided bracelet Hopper always wears, made from his late daughter's hair ribbon, at her school dance in the season two finale. All the tears!

14. Eleven's season one kiss with Mike was Brown's first kiss ever. "He says I wasn't, but I definitely think I was," Brown told Variety, teasing her co-star in absentia. "I think he was just trying to be cool."

15. And when the pair had to smooch again the following season, Brown revealed what her co-star whispered in her ear.

"He wanted to let me know he was, like, kissing me then," she explained during a 2017 appearance on The Tonight Show. "So he was like, 'I'm coming in,' and he was like a ventriloquist! It was the craziest thing."

16. Natalia Dyer and Charlie Heaton, who play love interests Nancy and Jonathan, began dating in 2016, but have mostly kept their relationship private.

"That's something important to me—with my family, with my friends, I really like to keep it for me," Dyer told Refinery 29 in 2019, though she did admit, "It's an interesting thing to work with somebody who you go home with. It's always really fun."

17. Believe it or not, two fan-favorite characters were not supposed to make it out of seaso one alive, including Joe Keery's well-coiffed Steve Harrington, who was initially scripted to be the bad boyfriend before the actor was cast.

"We love Joe. We fell in love with him during the making of season one, which is why we ended up writing that arc for him where he's helping to save the day with Jonathan [Charlie Heaton] and Nancy," Ross told The Hollywood Reporter in 2017. "Steve was supposed to be this jocky douchebag, and Joe was so much more than that."

18. Also slated to perish was Eleven. Yes, really. 

"Eleven was going to sacrifice herself to save the day," Ross said in the 2018 book Stranger Things: Worlds Turned Upside Down. "That was always the end game. But once we realized that the show was potentially going to go on longer than one season, we needed to leave it more up in the air, because deep down we knew the show just wouldn't really work without Eleven. And at that point, we knew how special Millie was. If there was going to be more Stranger Things, Eleven had to come back."

19. The seventh episode of season two—titled "The Lost Sister"—almost never made it to air, with the Duffer brothers telling Vulture in 2017 that they were concerned the outing, which centers on Eleven going off to find another child who was experimented on, would break up the story's pacing.

"When we got to the point of writing the episode, we wanted to see if we really needed it or not," Matt explained. "We actually did toy with pulling the episode completely, but then the ending with Eleven didn't work at all. It just didn't land at all. Then we ended up deciding we needed it."

20. Eleven's sibling was written to be a boy, with the episode originally titled "The Lost Brother." 

But after the audition was opened up to all young actors, it was Linnea Berthelsen who landed the part, and the episode ultimately featured Eleven meeting her "sister" Kali, another child Dr. Brenner (Matthew Modine) experimented on in the lab.

"Linnea and Millie really had a connection," Matt said, "Millie was like, 'I want to do this with Linnea.'"

21. Bridgerton actress Nicola Coughlan told Buzzfeed that she initially auditioned for the role of Robin in Stranger Things before booking the role of Penelope Featherington years later. Maya Hawke ultimately nabbed the part, with Coughlan saying Hawke was "was far better than I ever would have been."

She added, "It's a good lesson to actors: Watch the stuff you didn't get, because you'll totally understand how it's not personal. You're just right for some things and you're not right for other things."

22. Before playing Sarah on Netflix's Outer Banks, Madelyn Cline appeared in season two as Hawkins High school mean girl Tina. 

23. To win the part of Billy, the mullet-rocking bad boy older stepbrother of Max (Sadie Sink), Australian actor Dacre Montgomery filmed a fun, yet slightly raunchy, audition tape, telling GQ he "wanted to make a bit of a splash with the Duffers."

That meant filming himself dancing to classic 1980s songs like "Come on Eileen" and "Hungry Like the Wolf" in nothing but a G-string. Montgomery admitted he had some hesitation about sending it, saying, "Either I'm never going to work again, or somebody somewhere is going to see one thing in me, and they'll give me a chance." Fortunately, his risk paid off.

24. Heading into season three, Deadline reported that the cast received major pay increases, with the younger cast—including Wolfhard, Brown, Matarazzo, Schnapp and McLaughlin—going from about $30,000 per episode to more than $200,000 per outing, and possibly even $250,000. Ryder and Harbour, meanwhile, were reportedly taking home about $300,000 to $350,000 per episode, while Dyer and Heaton were making $100,000 to $150,000 per episode.

25. While Priah Ferguson was intended to only appear in one episode in season two as Erica, Lucas' sassy little sister, the Duffer brothers kept finding ways to add the scene-stealer. Ferguson was made a series regular the following season.

26. Given that the younger cast was still growing as the series was filming, the wardrobe department faced a unique challenge when it came to continuity. 

"It's crazy," season two costume designer Kim Wilcox told E! News in 2017. "We had one kid we could not keep in shoes, like every three weeks he grew a half-size." Her solution was to find heritage brands that make the same product in multiple sizes. "We'd buy five of them so that when somebody grew we'd have something."

27. While the Duffers were paying homage to movies they loved growing up, including The Goonies, E.T., and Stand By Me, they were cautious not to be too overt in their references.

"When we billed the project to Netflix, we had this big two-and-a-half-minute trailer that had about 20 or 30 of these movies kind of woven together to try and tell the story of Stranger Things, but obviously all these images or ideas were in our heads," Matt told The Daily Beast in 2016. "Those are the movies that we grew up on and they're so much a part of our DNA. But then when you get into the writers' room and you're working on individual episodes, actually very little time is spent referencing other movies. Mostly you're just trying to tell the story, letting the characters guide where everything's going. Otherwise it would just be a jumble and a mess."

28. The creative team set out to use as little special effects as possible to achieve a throwback feel, but quickly learned how difficult that would be.

"The funny thing is that the original goal was to do entirely practical effects. But what we realized—and it really made us admire those guys who did The Thing and Alien and whatever—is that doing practical is really hard," Ross explained. "It takes a lot of time and preparation. We were turning out scripts as quickly as we could but they don't have six months to prep this stuff. You show up on set and stuff that seemed like it would be a great idea to do in that old school way, we didn't have time to do."

29. When they first pitched the show, the Duffers always envisioned a five-season arc. "So much of what they had in their head in 2015 is what we're now seeing play out as we come to the end of this series," Netflix executive Matthew Thunell told Variety, with the magazine reporting that each of season four's episodes cost $30 million.

30. While an ending for Stranger Things has been set, the Duffer brothers aren't ready to leave the Upside Down just yet.

"We do have an idea for a spin-off that we're super excited about," they said in an email interview with Variety, "but we haven't told anyone the idea yet, much less written it."

Despite their efforts to keep it a surprise, Matt and Ross admitted that Wolfhard already guessed the premise of the series, which they described as "very, very different." They added, "Aside from Finn, no one else knows!"

Stranger Things is streaming on Netflix.

This story was originally published on Monday, May 30, 2022 at 3 a.m. PT.