#1 In “Toy Story 4,” Mr Potato Head Is Voiced Posthumously By Don Rickles (Who Passed Away In 2017)

#2 In The Pixar Logo After The Credits Of Wall-E, Wall-E Replaces Luxo Jr.’s Lightbulb With An Environmental Friendly Bulb After His “Round” Bulb Goes Out

#3 In Up (2009), Dug Is The Only Dog To Successfully Track Down The Tropical Bird Because He Is The Only Hunting Dog (Golden Retriever). All The Others Are Guard Dog Breeds

The animation studio likes to make constant but subtle references in its movies. Not only does it sprinkle little hints that help tie each film in with all the others, but it also likes to refer to the real world. Not to mention all the metaphors hidden throughout!
It’s because of these hidden details that there are plenty of people out there who believe that every single Pixar movie happens in the same universe and that each film is connected. In fact, hidden details have inspired some fans to try and piece all the movies together into a single, coherent timeline.
#4 Whenever Characters Play Guitar In The Movie, Their Hands Form The Actual Chords Corresponding To The Music... Even Though It Would've Been Easy To Just Fake It

#5 In "Up" (2009), Ellie's Things Are Rounded While Carl's Things Are Square, Matching Their Respective Character Designs

#6 Incredibles (2004) Elastagirl’s Original Suit Was Red And Mr. Incredible’s Suit Was Blue, Their First Child’s Name? Violet

For example, Jon Negroni has painstakingly outlined just what happens in this universe by creating the so-called Pixar Theory.
Others have even created websites like this one based on that theory. (Spoiler alert, apparently, Monsters, Inc. happens sometime between the year 4500 and 5000, and involves time travel because humans have, supposedly, been wiped out.)
#7 For Monsters Inc. (2001) Due To Mary Gibbs Who Played Boo Being So Young, It Was Difficult To Get Her To Stay In The Recording Booth To Perform Her Lines. So They Decided To Follow Her Around With A Microphone And Cut Her Lines Together Using The Random Things/Noises She Say Whilst Playing

#8 When Mike Marks An X On The Calendar In Red Marker, It's Brighter And Fresher Than The Rest Of The Marks, Which Have Dried

#10 In Finding Dory, Jacques's Bag Is Cleaner Than All The Other Bags. This Is Because He's A Skunk Cleaner Shrimp, Which Means He Eats Dead Tissue And Other Organisms

#11 In Finding Nemo (2003), Gill Is A Moorish Idol. This Species Is Known To Not Handle Captivity Well, So Him Being The One Who Constantly Comes Up With Escape Plans Makes Sense

#13 In Inside Out (2015), Riley's Clothes Become More Muted As She Becomes More Depressed Throughout The Movie

#14 In The Incredibles 2, The Painting In Helen’s Hotel Room Is An Illustration Of Her Seperation From The Family

#16 The Playing Cards In Riley's Imagination Feature Her Dad's Face As The King, Her Mom's Face As The Queen, And Her Face As The Jack (Except The J Is Changed To An R For "Riley")

#17 For A Scene In Ratatouille (2007) Where Linguini Is Wet From Jumping In The River, They Got A Member Of Crew (Kesten Migdal) To Jump In A Swimming Pool In A Chef's Uniform To See Where The Uniform Would Normally Stick To On The Body When Wet

#18 In One Closeup Shot, You Can See That Andy Marked The Height Of His Various Toys Against The Door Jamb

#19 In Inside Out, The Pizza Toppings Were Changed From Broccolis To Bell Peppers In Japan, Since Kids In Japan Don’t Like Bell Peppers. Pixar Localised The Joke

#20 For Brave (2012), Pixar Developed Two New Software Programs Over Three Years To Allow Simulation Of Merida's 1,500 Strands Of Hair Curls To Move Together With Her Movements






