Back To The Future
As the first trailers confirmed, Robert Zemeckis' Back To The Future plays a big role in Ready Player One and it's one of the most affectionately celebrated reference points in there.
133. Z's DeLorean
He might not be the richest player in The OASIS, but Parzival does have one big thing in his armoury - a fully working (well, not time travelling) DeLorean, which is unveiled during the race for the first key and then reappears for the film's climactic battle. And of course, he has personalised plates.
132. "Marty McFly"
Art3mis refers to Parzival as Michael J. Fox‘s character “Marty McFly” at one point, presumably because the first time they meet it's in the race and he's in the DeLorean.
131. Mayor Goldie
In the scene that sees Parzival & Aech discussing who Art3mis may be in the 'Real World' (when Aech gives away the fact that her avatar is nothing like her), there's a Mayor Goldie Wilson election poster on one of the walls in the background.
130. The Zemeckis Cube
After Z wins the first key, he spends his winnings upgrading his inventory including buying a Zemeckis Cube, which looks suspiciously like a normal Rubiks Cube (it wouldn't be an 80s movie without one of those). But when he's forced to use it, the name's relevance is explained: the cube turns time back for a minute to allow the user to escape.
And in case you missed the reference to Back To The Future, Parzival activating it is the cue for the BTTF theme to play.
129. The Hoverboard
There's a Hoverboard from Back to The Future II in Aech's apartment.
128. Doc Brown
At one point in The OASIS, there's a Doc Brown avatar, which is as inevitable as it is shocking that there's no actual Marty McFly.