The one thing everyone talks about w/r/t Stranger Things is its references to 70s and 80s sci-fi, adventure, and horror films. As this video by Ulysse Thevenon shows, there's good reason for that...the references are many and explicit.
The ones I noticed the most were to E.T., The Goonies, and Explorers, which I just watched again recently and doesn't hold up very well in a lot of ways. I also feel like there might be a bit of D.A.R.Y.L. in there too, but I haven't seen that movie since I was 12. See also Every Spielberg Reference in Stranger Things.