The movie that Mr. Clark (Randy Havens) and a lady friend are watching is John Carpenter's The Thing (1982), which contains a monster whose head opens up like the petals of a flower, much like the Demogorgon.
The show-runners (Matt Duffer) and (Ross Duffer) revealed that this episode was their most purely "fun" episode of the season because of featuring the bike chase scene with the kids, and following up with a "crazy van flip" sequence. Originally, they didn't have a bike chase planned for the episode, but opted to go for it as they felt it fitting to the plot, aside from recalling the famous chase scene from E.T. the Extra-Terrestrial (1982).
The dining chairs and floor pattern of the Wheeler house are the same as those in Poltergeist (1982).
The scene that sees Hopper (David Harbour) burst into the bus to rescue the kids was purposefully shot to resemble Indiana Jones and the Temple of Doom (1984).