#18: What a Goonie
Everyone who watched season 2 of Stranger Things fell in love with Bob, played by Sean Astin. Not only did he care so much for Joyce, but he was also so incredibly brave and willing to do whatever it took in order to help her find Will.
But little did we know that just by casting Sean Astin, there was a clear reference to a different 80s film directed by Richard Donner, The Goonies. There were enough references without Sean Astin, such as the many unsupervised bike riding trips, but now the correlation between the two films is even clearer.