Along with the Mirkwood reference to Lord of the Rings/the Hobbit, there is a second reference to the J.R.R. Tolkien novels. When Joyce (Winona Ryder) has a flashback to talking to Will (Noah Schnapp) in his Castle Byers hideout, she has to give him the password first. The password is Radagast, the name of one of the Wizards from Tolkien's novels.
Many aspects of the opening of the episode are influenced by E.T. the Extra-Terrestrial (1982). The opening scene of Stranger Things (2016) starts with the camera panning down from the sky, just like the opening of E.T. Also, the main characters in the film play Dungeons & Dragons and order pizza at the beginning of E.T., which helped popularize the game in the eighties. The Duffer Brothers (Matt Duffer and Ross Duffer) stated that the scene where Will Byers (Noah Schnapp) goes into the shed is a "blatant" homage to E.T., in which the main character goes into the shed and makes first contact with the titular character.
The scene in which Chief Hopper (David Harbour) types the police report was intentionally framed identically to a scene in Jaws (1975) which is one of 'The Duffer Brothers' (Matt Duffer and Ross Duffer) favorite films.
When introducing the four boys, they are playing Dungeons and Dragons. This is an homage to E.T. the Extra-Terrestrial (1982), in which the protagonists are introduced while playing Dungeons and Dragons.
The scene where the three boys pull up to the edge of the woods at night with their bikes, is a reference to the scene in The Goonies (1985) when the boys first pull up outside the Fratelli's hideout on their bikes. The music is almost identical, as is the conversation. The character of Barbara 'Barb' Holland (Shannon Purser) also seems to have been inspired by Stephanie Steinbrenner (Martha Plimpton) from The Goonies, who also had huge glasses, wore her hair in a perm, and whose name was similarly abbreviated to "Stef".