1.In Hercules, the Fates sing about the planets aligning. However, only six planets are shown...this is because the ancient Greeks only knew of the five planets (plus Earth) visible to the naked eye.
2.When entering Phil's house, Herc hits his head on the mast of the Argo. In the original Greek myth, Jason died when the ship's mast hit him in the head.
3.In Aladdin, the genie sings that "Scheherezade had a thousand tales." In Arabian folklore, Sceherezade actually had 1,001 tales*, but Aladdin was one of them, so the characters in the movie would probably only know 1,000.
4.The Genie's outfit at the end of the movie is a nod to this outfit Robin Williams wore in a video Disney shot back in 1989 for MGM Studios (now Hollywood Studios) at Disney World.
5.When Genie takes Aladdin's order, he writes from right to left, the way Arabic would be written.
6.In Mulan, Mulan lists "punctual" as one of the qualities a bride supposedly needs to have. This references Aladdin, where Genie accidentally feeds Aladdin the same word.
7.In Tangled, Mother Gothel always kisses/touches Rapunzel's hair when she says "I love you most." This signifies that she doesn't love Rapunzel, she only loves her magical hair.
8.Rapunzel's mobile over her crib had animals and charms that foreshadowed characters in the movie.
9.The lantern that Rapunzel touches during "I See the Light" is the one her parents — the king and queen — lit. It's the only one with the royal symbol on it.
10.In The Princess and the Frog, the wallpaper behind the evil Dr. Facilier turns into skulls and crossbones where his shadow hits.
11.When Tiana is walking through New Orleans, a lady is shaking out a carpet on a balcony. The carpet looks exactly like the magic carpet from Aladdin.
12.In The Rescuers, Orville the albatross uses a runway to start flying. This is a funny gag, but it's also true to life: Albatrosses are so large that they usually need a running start in order to take off.
13.In Moana, when Maui turns into a half-shark, his tiny tattoo version also has a shark head.
14.Hei-Hei tries to eat a "rock" more than once (since Dwayne "The Rock" Johnson voiced Maui).
15.Whenever Maui transforms, since he isn't holding his hook anymore, the hook appears somewhere in the markings on his body.
16.In The Lion King, all of the lions extend their claws when they need them and retract them when they don't...but Scar's claws are always out.
17.Simba learned the maneuver he uses to defeat Scar from Nala, who reverses his pounces twice.
18.In Lilo & Stitch, Lilo believes that Pudge the fish can control the weather, and gives him sandwiches to keep him happy. It's never stated outright, but Lilo likely wants to appease Pudge because her parents died in a car accident on a rainy night, so she wants the weather to always be nice.
19.The adoption papers in Lilo & Stitch are actually a thank-you letter to everybody who worked on the film, written by the directors and producer.
20.In The Hunchback of Notre Dame, Frollo offers pieces of silver in exchange for information about Esmerelda. He increases his offer but stops before offering 30 pieces of silver, as that was the price that Judas accepted. Since Frollo was such a religious zealot, he would steer clear of that act.
21.During "Hellfire," the light around Frollo is shaped like a coffin.
22.In The Jungle Book (2017), Mowgli picks up a cowbell right before King Louie appears. King Louie is voiced by Christopher Walken, who was obsessed with "more cowbell" in a famous SNL sketch.
23.In Zootopia, Nick's application shows that he initially ticked "yes" in response to a question asking if he had ever been arrested, but he crossed it out and ticked "no."
24.Nick kept his scout kerchief, which he still uses as a handkerchief as an adult.
25.When Judy chases a perp through Little Rodentia, there's an ad for "Thigmo-Taxis." Thigmotaxis is the scientific name for a biological response to move toward or away from touch stimulus, and has been studied extensively in lab mice.
26.Zootopia's dollar bills have bucks on them. A buck on a buck. Get it?
27.The high score in Wreck-It Ralph is 120501, which is a reference to Walt Disney's birthday: December 5th, 1901.
28.In Ralph Breaks the Internet, Ariel's candlestick and box of "thingamabobs" (she's got 20) is visible in the background on the vanity table.
29.One of the spammy pop-up ads that approaches Ralph tells him that "sassy housewives" want to meet him. The ad shows a photo of Aunt Cass from Big Hero 6.
30.In Beauty and the Beast, all the people/objects in the castle have punny names. The ottoman is named Sultan, because sultans were rulers in the Ottoman Empire.
31.When Gaston falls to his death, two skulls appear in the pupils of his eyes.
32.In Beauty and the Beast (2017), Le Fou slips coins to some of the bar patrons during the "Gaston" song, in order to bribe them into joining in and boost Gaston's ego.
33.In Pirates of the Caribbean, Jack tells a group of prisoners trying to lure a dog that the dog "isn't going to move." This is a reference to the titular theme park ride, which has a similar dog that's been in the ride since it opened.
34.When Commodore Norrington holds the compass — which points toward the thing the holder wants most — it points toward Jack Sparrow, indicating that Norrington's greatest desire is to arrest Jack and get a promotion because of it.
35.In Big Hero 6, Honey Lemon's purse has a periodic table of buttons on it. This means she's actually creating chemical formulae on the fly using the device.
36.In The Little Mermaid, Ursula uses a butterfly in her spell to transform herself into "Vanessa"...Vanessa is also the name of a genus of butterfly.
37.When Prince Eric first sees Ariel after she saves him, she's backlit, making her hair appear darker. This may be why Ursula chose black hair in her transformation, to help fool Eric into thinking she was the one who saved him.