In 9, if you pause before 8 walks in front of one of the statue bases, whilst outside the library, you'll be able to read the sign in the background: "Cheer bad and cheer good and shadows which we cast". Not sure whether it means anything, but it sounds cool.
On the left side of that background, there is a wanted poster for Flynn Rider as well. And there are likely several in Hiro and Tadashi's room with all the action figures and posters. A prominent one appears to be a large clock using either Gigantor or a Mazinger, though the arms seem to always be showing the same time throughout.
Hans makes another appearance, as the Statue, which Baymax tests his Rocket Fists on.
One of Fred's throw pillows features the face of Stitch, as does one of the framed photos in Hiro's house.
One of Stitch's cousins (Experiment 619/Splodyhead) appears on another pillow next to the Stitch pillow.
When the gang is talking in Fred's den, there are models of the Marvel villains Black Talon and Orka in the background.
The Canadian animated short The Big Snit is packed with visual gags that are only on screen for a few frames, especially in scenes of panic resulting from the announcement that nuclear war has broken out.
The scenes of panic in the streets include a motorcycle driving over the cars on the road, a car seemingly being driven by a pack of dogs, a man in a turtle-drawn chariot, a telephone box being pushed along in front of a car, a man in just the back half of a car holding onto the fender of the car in front of him, a car somehow driving while upside-down, Noah's Ark (on the road, no less), a man sleeping peacefully in his bed somehow keeping pace with the cars around him, a steam engine, and a man on a hostess trolley.
A high altitude shot of nuclear missiles flying all over the world includes a shot of Santa Claus and his sleigh and reindeer - complete with the sound of jingle bells.
When the bombs hit, sending the protagonist couple (and their cat and parrot) to heaven immediately, a collection of Scrabble tiles reading "HOTEL 10 KM" floats on screen for a few frames.
Characters from El Tigre appear in a crowd shot in the 2D animated prologue.
At the very end of the movie, when Xibalba and La Muerte kiss, they form the Sacred Heart.
Brother Bear 2: While Kenai escapes with Koda from the villagers, Atka hurls his spear at the bears, grazing Kenai's shoulder. At that moment, blood actually sprays from the wound, averting Bloodless Carnage as it usually is in Disney sequels. The blood shows up again when Kenai tries crawling through two rocks to escape (where it smears the top rock), and again when Nita cleans his wound after he's shoved off a cliff.
When Cinderella gains her magic ballroom gown from the Fairy Godmother for the very first time, if you pause at the right moment when she is spinning in her said gown, for a split-second you can actually see her in the very pose they used as stock clip-art for her merchandise.
The Rope Bridge sequence in The Emperor's New Groove features a moment when some boards fall into the chasm; if you slow it down enough, you can see they are stylized letters spelling out "D-A-M-N".
In the first, there are several bonuses that count as foreshadowing examples, and might be overlooked until another character's story gets told.
If you look carefully during Red's mine cart ride with Japeth, when they pop out of the tunnel, you see the drop they go down with a POV shot. Another driverless cart can be seen scooting by on the track Red's cart goes under. You might make out two individuals on it. When you freeze it, you will notice the Wolf and Twitchy. In turn, when the Wolf gets to this point in the story, (just after he says "Now this is a shortcut!") they pass by another track that has a steep drop down the hillside that goes under their cart's track, and you hear a scream as a cart drops in the background. Freeze the image at the moment of the scream, and you can see Red dropping in her mine cart.
When Red is looking at the map of the mine tunnels in Japeth's shack during "Be Prepared," if you freeze it, you'll see places with such punny names like Puckett Grove, Sam Hill, Kanbar Kanyon, the Blue Yonder, Murphy's Low, Boulderdash, and something that looks like it says "Old Man's Cave" (partially obscured by Red's head).
When Red is in the treehouse and reading a travel magazine, if you freeze at the right time, you'll see that she's looking at a cartoon of what appears to be a rhino and zebra having tea.
When Red falls from the cable car, right before she slips, Boingo's grab is far more at her basket than her. Also, when Red is plummeting, you can see him looking down at her - but his expression is one of anger rather than one of concern.
Red's confrontation with the Wolf has her use Mace spray on him. If you freeze the image at the moment she pulls it out, either in her story or in the Wolf's story, it clearly says "Wolf Away Spray". Which leads to the revelation that Red is Crazy-Prepared.
Twitchy only makes a three second cameo in Red's story, during the bit where a flashbulb in his mouth goes off.
When Boingo is Storyboarding the Apocalypse to Red, you can see that his proposed "Boingoland" will extend into Smallville, and also has an airport, an amusement park, and a lot of other intersting things relating to him.
In the second, the recipe for the MacGuffin is briefly on screen. If you freeze the image, you can see amusing fantasy-story entries like Sleeping Beauty's morning coffee, but right at the bottom is Soylent Green, crossed out with "People!" written beside it.
Carpet is in the same shot as Belle in Hunchback. Carpet also pops up near the start of The Princess and the Frog, which has several other references by that point.
With Director Commentary; If you look, in an aerial shot of Paris, in Hunchback Of Notre Dame, one of the buildings has a Satellite Dish◊!?
Pumbaa shows up in Hunchback too — as a roast pig on a spit.
Justice League: Crisis on Two Earths: A computer display briefly shows an assortment of identifiable counterparts of various superheroes as supervillain "Made Men" working for the Syndicate.
In Kung Fu Panda, in the "you are free to eat" scene, if you pause just as Shifu snatches away the first dumpling Po tries to eat, you can see he's practically making a Troll Face.
In Kung Fu Panda 2, during the scene where the heroes are captured and Po puts Mantis inside a cage, you can scroll along frame-by-frame and see Po swapping out the real Mantis with his wooden action figure.
Kung Fu Panda 3 has several extremely brief shots of Tai Lung, the first film's antagonist, as one of the jade amulets on Kai's belt.
In Lilo & Stitch, Stitch hits Jumba with the VW Beetle and knocks him into Nani's bed, over which hangs a poster of surfing legend Duke Kahanamoku. When Stitch pins Jumba with the Beetle, Duke briefly has a shocked expression on his face, visible for only a fraction of a second.
In Monsters, Inc., when Sulley is grabbing Boo's keycard as they're fleeing from Randall's lair, you can see a report on Boo listing several statistics, such as her race being Hispanic, she wets the bed, and she has a phobia of snakes (hence why Randall was assigned to her).
The video game AJ and RD are playing at the Slumber Party has a humanized version of the Mane-iac on the cover.
As Twilight struggles to write a song, she stares forlornly at a page full of scribbles and doodles... including one of her disembodied head spitting lightning bolts at a crudely-drawn Adagio.
While listening to "Under Our Spell", Luna has drawn a heart on her notes.
Vinyl Scratch's car (before transforming) has a hood ornament shaped like DJ Pon-3's unicorn counterpart.
During the production of The Rescuers, one of the animators decided to pull off a prank, and inserted an image from Playboy into a few of the frames. Normal viewing could not reveal anything, but a careful freeze frame did. When it was spotted by Disney, the image was edited, and all subsequent VHS and DVD editions were Playboy-free.
Bernard's current cover pose for The Rescuers can be seen for a few frames during the "Tomorrow Is Another Day" montage to Devil's Bayou.
When Terrence and Phillip are getting shocked on their chairs, you can see that Kyle has pissed himself.
During the "Blame Canada" number, Sheila shows her group a newspaper headline about Terrence and Phillip appearing on Late Night with Conan O'Brien later that night. Other headlines on the front page read "Poop Declared Edible" and "Christians Agree: Guns Are Nifty".
A couple of the flags outside the United Nations building are a rainbow pride flag and a Jolly Roger.
One of the South Park men going to war is Jesus, complete with halo over his helmet.
One such bonus in Spider-Man: Into the Spider-Verse contains a subtle hint about the film's plot that many won't catch on the first viewing: during Spider-Man's narrated origin story in the beginning of the film, as he's pulling his mask on, one can see that Peter Parker's hair is blonde instead of brown like the alternate-universe counterpart that appears later on.
Storks: It goes by quick, but when Pigeon Toady is showing off his 'girlfriend' (which is a picture of a live-action Canada goose) you can see that he actually pulled the picture up in a Google image search.
The Thief and the Cobbler has a scene where the eponymous Thief is shot out of a cannon. If one freeze-frames the movie at the scene where the Thief is facing the camera, the flies perpetually circling his head turn out to be minature Thieves with wings, a testament to the animators' talent and determination.
Toy Story 2 did this with the scene where Buzz is karate-chopping through the bush — look real closely at the last twig he chops: there is a tiny caterpillar crawling across it. This instance was later referenced in the bloopers with Flick and Heimlich appearing on it.
Also, when Hamm is flipping the channels looking for the Al's Toy Barn commercial, the images that flash by are from older Pixar shorts and commercials.
Not to mention the Pixar Star Ball popping up everywhere...
Toy Story 3 had a moment where if you paid close attention it was possible to see that one of the two garbage men is Sid from the first movie.
Many, many jokes and sight-gags in the background, especially signage containing brand names, or Duke Weaselton's display of pirated DVDs.
On the Wrangled DVD cover, Rapunzel (who in this universe is a horse) is holding her hair in the same pose as the cover of Tangled. However, if you look closely, you'll see that 1) the hair she's holding is actually her tail, and 2) there's an extra length of hair strewn across the grass compared to the Tangled cover. That's the end of her mane.
As Judy comes out of the train station after first arriving at Zootopia, several Junior Ranger Scouts (of the sort Nick wanted to join) can be seen to her left.
The Pig getting her picture taken at the DMV is also the prison guard seen in the end credits.
Near Bellwether's desk is a sticky note that has Doug's phone number on it, tying her to him.
When Nick gives Judy his filled-out application form, one question asks if he's been arrested or charged in the past. You can see he initially checked "Yes", but then scribbled it out and boldly checks "No" instead. This is accurate, as he indicated earlier he's never been arrested before and he realized Judy's tax evasion arrest didn't count — at no time was he read his rights or placed in police custody, so he was never officially under arrest.
The rabbit mannequin used in the Natural History Museum is a saber-toothed Jackalope.
During the Little Rodentia chase scene, there is an advertisement for Thigmo taxi services. Thigmotaxis is a behavior in mice where they cling to solid objects, which one of the mice is understandably demonstrating when Weaselton starts knocking over houses.
When Judy goes back to Bunnyburrow after quitting the force, you can see a copy of the Bunnyburrow Beacon with an assortment of small town news articles, including one on the Population: X, and Counting sign getting a new coat of paint, an article about the annual Carrot Days Festival (and an advertisement for same), and Otto Hopps (Judy's grandfather, who's also seen in a few deleted scenes) celebrating his 101st birthday.
Towards the end of the movie, when the three officers are assigned to undercover, Snarlov, the polar bear officer, simply puts on a baseball cap as his "disguise". It's also the same baseball cap worn by Judy's father, Stu, throughout the film: a light green cap with a dark green front and a carrot label on the front.