Ready Player One promised fans many things, but nothing was quite so tantalizing as the potentially endless amount of Easter eggs hidden throughout the film. There was a lot of talk before the film came out about the difficulty of acquiring the rights to display so many different properties. After all, the references in Ready Player One practically outnumber original content. Because the film is distributed by Warner Bros., many of the Easter eggs in Ready Player One are from films and properties Warner Bros. already owns. The most obvious example is turning Ultraman (who was prominent in the book) into the Iron Giant (who comes from a Warner Bros. movie).
Not that any of this is noticeable when watching the film. Half the fun is trying to take stock of every reference sprinkled throughout the background, and while some are easy like Wade driving the Delorean, we're willing to bet you didn't notice every Easter egg Spielberg crammed in there.
It's hard to really take in the environment during the race, but there's one cool little Easter egg that stands out if you look closely. At one point, the racers whizz past an old-school marquee theater advertising a showing of The Last Action Hero. For those that aren't familiar, it's a cult-classic Arnold Schwarzenegger film, and it also features an absurd amount of action.
At one point during the film, a "Save Ferris" poster can be seen hanging off of a desk in the IOI headquarters. This is a reference to the spray painting on the water tower in Ferris Bueller's Day Off.
Prior to the final battle for the Oasis, Nolan Sorrento uses the Orb of Osuvox for a little extra protection. One activated, the orb activates an impenetrable force field that should last for "ten million years." The orb is turned on and off by chanting a magic spell. Specifically, one of the spells spoken in the 1981 film Excalibur.
During the final shootout with I-R0k, Artemis and Wade are frantically conjuring up and using different weapons to try and take I-R0k down. At one point, Artemis pulls up and begins firing a lancer from Gears of War. It's just too bad she didn't have a chance to engage the chainsaw bayonet.