Stranger Things season 3 contains a big twist: it references the 1990s. While the show is known and loved for its references to 1980s pop-culture, from the work of Stephen King and John Carpenter to products such as New Coke, the new season of Stranger Things takes things forward a decade with a number of its Easter eggs and references.
One of the biggest 80s movie references in Stranger Things season 3 is the presence of Grigori, who is basically the show's version of The Terminator. The parallels with Arnold Schwarzenegger's iconic role are clear as day, but in terms of Grigori's abilities and actions, he actually fits very closely with Robert Patrick's T-1000 from Terminator 2: Judgment Day, which was released in... 1991! He even bears a resemblance to Patrick in T2, making this a reference not only to 1984's The Terminator, but Terminator 2: Judgment Day as well.
However, that isn't the only time Stranger Things season 3 breaks its own rules and references the 1990s. In the very first episode, we see Dustin return home from science camp and he has an electric hammer. The actual machinations of the hammer are shockingly similar to the one invented by Homer Simpson (with a little help from Thomas Edison) in The Simpsons' season 10 episode "The Wizard of Evergreen Terrace", which aired on September 20, 1998 - well over a decade from the time period of Stranger Things season 3.
There's also a nod to Jurassic Park too. When Mayor Kline is giving his big speech at the Fourth of July carnival, he ends it by saying "we spared no expense." This is clearly a reference to John Hammond in Jurassic Park, who says the phrase "spared no expense" multiple times throughout the movie. Stranger Things is heavily indebted to Steven Spielberg, but it's still a little surprising to see it referencing this movie of his, given it wasn't released until 1993. The scene in the Starcourt Mall, with the Mind Flayer being viewed in the side-mirror of the car, also feels like a nod towards the T-Rex from Jurassic Park too.
Finally, while Stranger Things has long worn its Alien influences on its sleeve, season 3 appears to pay homage to a scene from the lesser-appreciated Aliens 3. One scene between Nancy and the monster closely mimics that between Ripley and the Alien Queen from that movie, and again it was released in the 1990s, this time coming in 1992.
Of course, there's nothing inherently wrong with Stranger Things season 3 referencing the 90s. Since they're homages, rather than direct, in-universe references, it doesn't break the timeline, and just adds to the ever-growing catalog of Stranger Things movie references.