And the Duffers cited Mad Max: Fury Road to convince Eleven to shave her head
When the Stranger Things duo pitched the idea of a near-bald look for Eleven, actress Millie Bobby Brown and her parents were terrified. A magazine photo of Charlize Theron in Mad Max eventually convinced her it was "badass" idea.
An explanation for "the Upside Down" totally exists
The Duffer brothers have a 30-page document about "the Upside Down," and we didn't even get hints at everything that's in it. According to Ross Duffer, "If there was going to be a Season 2, we would reveal more of that 30-page document, but we'd still want to keep it from the point of view of our original characters."
The Duffers say the Upside Down is bad for human health
Living in the Upside Down for a week is going to have long-lasting negative effects on Will. At the end of the first season we can see Will inadvertently flash into the Upside Down, but humans from "our side" were never meant to live in the Upside Down for an extended period of time. "That's a place we wanted to go and potentially explore in Season 2. What effect does living in there for a week have on him?"