References to Upcoming Films

Some of Pixar's notorious Easter eggs are references to Pixar films that were still in production at the time of release, making them references to upcoming Pixar films. Although it hasn't been as consistent as some of their other Easter eggs, in recent years it has become a tradition for Pixar to put in each of their films a cameo of or an allusion to a character from their following film.

Instances

 * Monsters, Inc. - Clownfish, the main characters of Finding Nemo, are depicted three times:
 * Harryhausen's has a painted mural featuring a clownfish.
 * A Nemo model is seen hanging in the trailer where Randall is banished.
 * Boo gives Sulley a Nemo toy.
 * Finding Nemo has allusions to the two films that followed it:
 * A boy in the dentist's waiting room is reading a Mr. Incredible comic book, a reference at The Incredibles
 * A non-anthropomorphic version of Luigi from Cars drives by when the tank gang finally escapes.
 * The Incredibles - A non-anthropomorphic version of Doc Hudson from Cars is parked in a street of Metroville during the final battle.
 * Ratatouille: 
 * A shadow of Dug from Up is seen when Remy wanders in an apartment.
 * Hal, from WALL•E, also makes a cameo.
 * Your Friend the Rat - WALL•E from The eponymous film is the driver of the vehicle on Mars. This reference is unique as this was in a short not a movie.
 * WALL•E - Carl Fredricksen's walking stick in Up can be seen upside down (with the tennis balls attached to the feet) on two occasions. Firstly, when WALL•E is about to pull across the magnifying screen the walker is sitting behind the iPod. Secondly, when WALL•E falls down from the ceiling of his truck (after being knocked there by EVE), he collides with the walker.
 * Up - Lots-o'-Huggin' Bear from Toy Story 3 is placed next to the bed of a little girl.
 * Toy Story 3:
 * Finn McMissile from Cars 2 is featured on a poster in Andy's room.
 * Also in Andy's room is a "Newt Xing" sign, an allusion to newt. Even though newt was canceled, it had been set to be released in 2012 (two years after Toy Story 3), and as such, this was technically a reference to an upcoming film.
 * Cars 2 - A car-ified version of the DunBroch family tapestry from Brave appears in the Ye Left Turn Inn in London.
 * Brave - A wood engraving of Sulley appears in the witch's hut. Although Sulley is an original character from Monsters, Inc., this cameo was advertised as an allusion to Monsters University.
 * Monsters University - Toy versions of dinosaur characters from The Good Dinosaur appear in the Scare simulators used for the final event of the Scare Games.
 * Toy Story of Terror! - The paintings hung in the motel room depict dinosaurs under a tree, another allusion to The Good Dinosaur.
 * Toy Story That Time Forgot - According to director Steve Purcell, the three posters in Mason's gaming room were allusions to three of Pixar's upcoming films: Inside Out, Cars 3 and Coco.
 * Inside Out - Giant statues of Forrest Woodbush and Arlo from The Good Dinosaur are seen in Riley's memories of the road trip to San Francisco.
 * The Good Dinosaur - Hank from Finding Dory appears at the bottom of the water when Arlo learns to swim.
 * Finding Dory - The driver of the truck heading for Cleveland at the end of the film has a band-aid with an image of Lightning McQueen on his right hand, in honor of Cars 3.
 * Cars 3:
 * The image Cruz Ramirez displays to motivate a homesick trainee is a location from Coco.
 * Ernesto De La Cruz' guitar is hung on the wall behind the band playing at the Cotton Pin Bar at Thomasville.