Animaniacs: Half of the jokes require a viewer to be extra savvy on not just pop culture, but classic animation and their different associated tropes, classic theater and music, the ins and outs of both classic and modernnote 1980's and 1990's from when the series premierednote Classic and modern what?, a ton of psychological, sexual, science, historical, and political knowledge to get some of the more obscure jokes of the show. To whit, the very first joke of the very first short of the series revolves around Dr. Scratchinsniff, the series' resident psychiatrist, writing off actor Ronald Reagan's dreams of being president of the United States as "incurable dreams of grandeur".
Half of the comments made by Brian. Some of them require a pretty big knowledge of musicals. In fact, it can be said that 'Family Guy'' is nowhere near as funny unless you have a good knowledge in 80s and early 90s pop-culture.
Back in the earlier seasons particularly, there was an extra layer of funny for those who live or have lived in Rhode Island. Lately, however, they seemed to have abandoned that.
Lois: Nigel's charming! All British men are! Peter: Yeah, right... that's what they said about Benjamin Disraeli. [cut to Benjamin Disraeli at a writing desk] Disraeli:[scornfully addressing the camera] You don't even know who I am!
Another episode noted that Jesus's actual last name is Hong. Stewie even says "He's not sure where people are getting Christ from", a joke referencing that Christ is not Jesus's surname.
Futurama contained a large amount of jokes relating to scientific concepts. For example, a dating agency had a sign reading "discreet and discrete", a joke which would make more sense to mathematicians. (Although, Word of God says that it is a reference to discrete electronics, not mathematics.) Other jokes included binary, and not one but two bilingual bonuses in the form of "languages" (actually encrypted text) which the viewers were left to translate/decrypt for themselves.
There are so many mathematical jokes in Futurama that the writers did a special for the first movie's DVD with a real mathematician dedicated to explaining them.
Math isn't the only topic they do this with. How many people will get all the jokes about decades-old politics in "A Head In The Polls", for example? And not just the Nixon stuff, but the Bull Space Moose Party, which is a joke almost a century old.
Or the obscure webcomic joke, to boot.
"Wow, I love symposia!"
They note several of these jokes during the Creator Commentary. Following the explanation for the 'Aleph-Nought'-plex theater as "infinity, but a small form of infinitynote Specifically, it's an infinite quantity that can be indexed by the natural numbers, unlike, for instance, the set of all reals.", the voice actor for Fry chimed in:
Billy West: "That is the nerdiest thing in the universe. However, it's only the fifteenth nerdiest thing in Futurama..."
"It's so cold, my processor is running at peak efficiency!" -Bender, Bender's Big Score
It's probably the only TV show, ever, to include a homage to Isaac Asimov's Foundation novels, the Holophonor.
And the Professor bemoaning how a horse race was so close that it came to a "Quantum Finish", but they changed the outcome by measuring it.
Or the beer in Klein bottles, on display next to St. Pauli Exclusion Principle Girl beer.
In "The Honking", Bender sees a string of zeros and ones on the wall, and tells Fry and Leela it's gibberish, then sees it in a mirror and panics. The creators are very coy about the significance on the commentary, but anyone who bothers to check will find the backwards string, 1010011010, is the base-2 representation of 666.
"The Prisoner Of Benda" is full of these. The Couch Gag is "What happens in Cygnus X-1, stays in Cygnus X-1" — a fact that's almost certainly true, since Cygnus X-1 is the most famous observed black hole candidate. Then Bender proves he's a robot through a reverse Turing test. Finally, at the end of the episode, the Globetrotters use abstract algebra to sort everyone back into their proper bodies. Naturally, the math checks out. And they said math has no practical applications!
Notably, the group theory proof used to resolve the plot was created just for this episode by Futurama writer with a PhD in applied math, Ken Keeler. The fandom and popular media were quick to dub it the "Futurama theorem".
"The Why of Fry" appears to take its name from "The Why of Y".note For the non-mathematicians/programmers - the Y combinator allows an anonymous function to be defined in terms of itself, exactly what Fry does to his own life during that episode.
In "Hell Is Other Robots", there's the Church of Robotology, whose logo is a jagged line, the schematic symbol for a resistor in electronics, i.e., "resisting temptation". The title is also a clear reference to Sarte's No Exit with the often quoted and poorly-understood line "Hell is other people".
In one episode, they go to a dance club called "Studio 1^2 2^1 3^3," the math adding up to "Studio 54."
In Law & Oracle, there is a reference to Erwin Schrödinger and the Schrödingers cat thought experiment:
URL: Erwin Schrödinger, huh? What's in the box, Schrödinger?
Schrödinger : Um... A cat, some poison, und a cesium atom.
Fry: The cat! Is it alive or dead? Alive or dead?!
URL: Answer him, fool.
Schrödinger : It's a superposition of both states until you open it and collapse the wave function.
(Fry enter the car)
Fry: Says you.
(Fry opens the box and a cat jumps out of it, attacking him. Fry screams. URL takes a close look at the box.)
URL: There's also a lotta drugs in there.
In "Love and Rocket", Bender (a robot) starts dating the crew's starship, Planet Express Ship, which has not spoken or been shown to have an AI until that point. Bender sings about his love with the song "Daisy Bell". This song was the first example of computer speech synthesis, which was done by IBM in 1961, and is a common shout-out. The panel through which Planet Express Ship speaks is shaped to look like HAL 9000 from 2001: A Space Odyssey, and HAL dies singing the song.
In one episode, the professor describes the ship's ability to travel faster than light by saying that it moves the universe around it rather than moving itself. While that sounds like ridiculous technobabble, the basic concept is used by a serious theoretical faster-than-life drive, the Alcubierre Drive.
In "Why Must I Be A Crustacean in Love?", it's revealed that Zoidberg's Cthulhumanoid species, the Decapodians, die after mating. Many species of real-life cephalopods do undergo post-mating senescence.
The same episode also makes a subtle reference to decapod crustacean anatomy. After Zoidberg's rampage at the gym, Professor Farnsworth examines Zoidberg and puts a stethoscope on his head. On the surface it looks like Farnsworth's engaging in his usual Cloudcuckoolander tendencies, but in real life, decapod crustaceans keep most of their internal organs, heart included, in their cephalothorax, commonly referred to as their "head".
On Rocko's Modern Life, the guys are making a cartoon and have some problems taking the film out of the camera with the lights off. When Heffer asks to turn the lights on to see what they are doing, Filburt says, "That'll expose the film, Eisenstein!" To most viewers, this will sound like a mispronunciation of Einstein; those familiar with film history will recognize it as a reference to Soviet silent film director Sergei Eisenstein.
Fillmore! contained a surprising number of these, in a addition to the regularly-spoofed cop show tropes, including a quick, but legitimate discussion of whether Judy Blume has subtext, and ShoutOuts to Charles Laskey, Miles Davis, Arthur Schopenhauer, and others.
The name Federico Fettuccine (the director character in "Lights! Action! Garfield!) is probably to many people an Italian-sounding name with a food reference. But to those with the right knowledge of film history, it's an obvious reference to Federico Fellini.
Mel Brooks also had a Fellini parody character named Federico Fettuccine in a comedy album he recorded in the early 60s.
Daria, being the genius that she was, often made quips at her family's expense in relation to literature she enjoyed. Odd for a teen animated show, most of the titles she referenced averted Small Reference Pools of teenage life.
Jake: "Why do they make sewing needles so damn SMALL?"
Homer: "He's nailing something to our door!" Lisa: "Hmm, I wonder if it's theses?"
Which, surprisingly, wasn't even close to the first "Martin Luther nails something to a cathedral door" joke in The Simpsons:
Lisa: I've created Lutherans!
In "Much Apu About Nothing", Chief Wiggum prepares his men to deport illegal immigrants:
"Alright, men, here is the order of deportation. First we'll be rounding up your tired, then your poor, then your huddled masses yearning to breathe free." Sounds familiar?
The Simpsons is full with references and in-jokes to history, science, math, politics, literature, music, comic strips, paintings, photographs, films, TV series, cartoons, urban legends, language,... that in many cases a huge chunk of it flies over the audience's head or may only be spotted and understood after repeated viewings.
The show is full of obscure — and accurate — mathematical references. You may be surprised to know that many of the writers possess advanced degrees in physics, mathematics and astronomy, among others. Many of the same writers moved on to to work on Futurama. Given the futuristic bent of the latter show, it's packed with even more scientific references.
This fact lends itself to a Genius Bonus from Arrested Development in which Michael refers to the child of Harvard alumni as "Probably some geek Simpsons writer's kid."
The "Homer 3D" episode was full of references to mathematical equations, physics and 3D graphics once he entered the 3D realm.
The UtahTeapot can be seen in the 3D world, as well as many 3D graphics primitives used as standard building blocks in 3D modeling, such as spheres, cubes and pyramids.
One of the equations in the background (1782^12 + 1841^12 = 1922^12) is very obscure. It almost disproves Fermat's Last Theorem, which states that such an equation should not be true. If you do it on your calculator, it seems to be correct - the error is in the eleventh decimal place, which is more than most calculators will display.
The place he's in is an Einsteinian representation of space-time and the vortex he creates is therefore a black hole which leads to an alternate universe.
The library from Myst also shows up, along with the music that plays when you are in front of it.
The chalk lines drawn on the wall where Homer vanished are a reference to the Twilight Zone episode "Little Girl Lost".
In the episode "Mountain of Madness", Mr. Burns says: I've seen more orderly behavior in a Ritz Brothers film!, a joke in itself obscure to most people (they were a dancing/comedy troupe), plus referencing H. P. Lovecraft's At the Mountains of Madness in the title.
In one of the "Treehouse of Horror XIII" shorts, several historical criminals come back as zombies, including the most evil German, Kaiser Wilhelm (Hitler was Austrian). This isn't as much a genius bonus as a "paid attention in 9th-grade history" bonus.
In one episode, Lisa is trying to complete a cryptic crossword with the clue "Yentl singer" (13). This is too short to be Barbara Streisand and Lisa is stuck until she triumphantly cries Isaac Bashevis.note Isaac Bashevis Singer was the author of Yentl the Yeshiva Boy, which the movie was based on.
The show also has some not-so-well hidden science jokes:
Homer (about Lisa's perpetual motion machine): In this house, we obey the laws of thermodynamics!
The villains in the episode "The Crepes of Wrath" are named César and Ugolin, which were the names of the antagonists in a pair of French novels, Jean de Florette, and Manon des Sources.
"The Homer They Fall" had Homer practicing a "technique" of just taking blows and letting his opponent tire out before fighting back. It sounds laughable to a casual viewer, but any real-life boxer will instantly recognize it as being based on the Rope-a-dope: an actual (and effective) technique that was notably used by Muhammad Ali to defeat George Foreman in 1974, and has been used to great effect in numerous other fights.
Discussed in "They Saved Lisa's Brain", the episode where the local branch of Mensa decides to take over the town. Comic Book Guy is wearing a T-shirt that says "C:/DOS C:/DOS/RUN RUN/DOS/RUN"
Lisa: ''[amused]] Only one in a million people would find that funny!
Prof. Frink: Yes, we call that the "Dennis Miller Ratio".
Lampshaded in "Treehouse of Horror XXV"'s A Clockwork Orange parody, which includes several references to other Stanley Kubrick films. For example. when Comic Book Guy, in 18th-century costume, loses his left leg at the knee he says "Even I forget what this is a reference to!" (It's to Barry Lyndon.)
In "Walking Big & Tall", it's shown at the beginning that Springfield's town anthem is actually a song sold to half the towns in America, with a short montage of many other locations, including some not in America. One of these is some stereotypical Mongolians whose dialogue is captioned as just "speaking foreign language", but if you listen closely, they're saying "Ulan Bator". Ulan Bator (or Ulaanbaatar) is a real Mongolian city—their capital, in fact.
In the episode "Return to Malice", 21 names his revenge scheme for 24's death "An Eye for an I." Go look up the Code Of Hammurabi.
Brock has just bisected an assassin, vertically. As he drags the body away, he tells Dean to get a phone number from his coat and call "The Cleaner" and tell him "we've got a 'Damien Hirst' in room 204". Hirst is a controversial conceptual artist who is known for, among other things, creating anatomical sculptures of humans with various layers of skin and muscle peeled back.
The episode "ORB" is positively dripping with this trope. A scene set in the late 19th century chronicles the precursors of The Guild and the OSI. Most people could probably recognize the references to Twain, Tesla, Wilde, and maybe even Crowley. But there probably weren't that many who knew that Fantomas was a character from a series of French novellas, or that Sandow was a real-life strongman and the father of bodybuilding. To take this trope to ridiculously meta levels, the characters attempt to solve a series of riddles using Wikipedia and end up entirely in the wrong place. The Alchemist calls them out on this, pointing out that the meanings of words change over time. He uses an old dictionary to prove his point and finds the location of the final clue.
In addition to being a parody of Wonder Woman, the character Warriana introduced in Season 6 incorporates a relatively obscure fact of the original mythological Amazons: she only has one breast. According to legend, the Amazons would amputate their right breast so that it would be easier to use a sword and bow in combat. She also refers to Brock, variously, as "Gargarean" and "Heracles", the former being a supposed all-male race which mated with the Amazons annually so that both their peoples can be propagated and the latter being the famous Greek hero who, in some versions of the Twelve Labors, had sex with the Amazons' queen Hippolyta. Naturally, this is foreshadowing to her and Brock becoming romantic partners.
In Fallen Arches, Triana is kidnapped by the Order of the Triad's new arch Torrid (and then rescued between episodes) by being magically sent to "the Torrid Zone" by the villain, which Orpheus deduces is in the tropics because he turned up between scenes that Torrid owns property there. This is more fitting than it might seem: Torrid is a fire-based demonic supervillain, and historically the tropics were thought to eventually turn into a "Torrid Zone" where it became so hot that anyone trying to cross it would eventually burst into flames, which was part of why attempts to cross the equator by Western civilization didn't take place until just a few centuries ago.
There's an example in VeggieTales - in Silly Songs with Larry, no less! During the song "I Love My Lips", while Archibald is showing Larry a series of Rorschach Test cards, near the end of the cards, if you pause just about 1:41, you see the number 6.023 x 10^23. For the average child, this is nonsense, which fits the song's theme. For people who know basic chemistry, this is Avogadro's Number.
There was a stand-up comedian who had a joke that, while in college at Lehigh, their basketball team once lost a game by Avogadro's Number. He then thanked the people who got that and laughed.
And another who, when performing in Fairfax, Virginia, said something about needing sunscreen that was SPF 6.022*10^23. One person laughed, but he laughed extremely hard.
In "Rhyme for Your Life", Binky is frustrated because he wants to write a poem on a birthday card for his mother, but he can't rhyme. He goes to sleep and dreams that he ends up in a magical land called Verseburg, where "It's a crime not to rhyme," and Verseburg's authorities throw him in jail for his inability to rhyme. Binky ends up sharing a cell with William Carlos Williams, a 20th-century poet famous for his use of "free verse" (poetry that doesn't rhyme), and Binky asks, "So you can't rhyme, either?" Williams answers, "Oh, I can rhyme—I just choose not to. FREE VERSE! FREE VERSE! I'm a political prisoner." Williams then shows him a secret passageway out of the cell and gives him a rhyming dictionary. A few minutes later, the episode mentions Walt Whitman and Pablo Neruda without any further explanation.
When Binky complains while wheeling Williams out of the cell, Williams quips, "Lucky you weren't imprisoned with Sylvia Plath - now she's a heavy poet!"
In "Take a Hike, Molly", Rattles mentions "a cave in Mexico where snakes hang from the ceiling and eat bats". Such a cave does exist in real life, called "Cave of the Hanging Snakes", and its location in Mexico is correct as well.
In one scene in "Squidward the Unfriendly Ghost", Squidward has tricked SpongeBob and Patrick into doing his every whim, and has them carry him around in a litter to various locations, which he dismisses as "Too hot" and "Too wet". They then stop in front of a background that looks like a fish-y version of a Moulin Rouge poster, which Squidward dismisses as "Too-louseLautrec!" Cue rimshot.
In "Tea at the Treedome", Patrick tells SpongeBob putting your pinkie up when drinking is fancy. It's not an incredibly known fact that doing so has the opposite effect and is impolite. It just shows Patrick's ignorance.
Goo Lagoon looks to be a silly idea, a body of water found on the seafloor that sea creatures treat the way land creatures treat bodies of water, complete with a shoreline. These are real: They are known by oceanographers as brine pools, and submersibles float in them making waves, though they are really only habitable to creatures adapted to them. This is explained on the official web-series Bikini Bottom Mysteries.
In "Krusty Kleaners", SpongeBob references the tradition of seppuku and does it with his spatula after spilling a milkshake. Being a sponge, it goes through one of his holes and doesn't harm him.
During a talent show in ReBoot, one comedian cracks a joke in binary, which is promptly derided for not being child-friendly. For those patient enough to translate it (or Google it), turns out to mean "Take my wife, please!".
That's just the tip of the iceberg. Any episode of ReBoot can basically be described as "24 minutes of computer jokes", some of which require intimate knowledge of computer hardware from the 80s and early 90s to understand.
There were also references that one wouldn't get unless one was very familiar with the show creators' previous work. In that same episode about the talent show, a more crudely-rendered handyman and younger man appear, who are promptly booed off-stage. This is a reference to the ReBoot creators' work on the (at the time) very cutting-edge CG in the 1985 music video for Dire Straits' "Money For Nothing."
Many characters and jokes are based off of actual CGI development terminology. In the case of Phong and Ray Tracer their namesakes were actual rendering tools that were important in their visual look (Phong is a gradual shading composition tool which is evidenced by his metallic head and Ray Tracing is about layers of opaque surface reflections that are reflected in his crystal-like body suit). Also in the "Talent Show" episode, one group of musicians called "The Primitives" consisted of a sphere, a cone and a cube, which are the basic shapes of CGI called "the primitives".
Archer frequently goes from jokes about anal and drunkenness to jokes about Indira Gandhi, Eugene V. Debs, and Herman Melville. "I would prefer not to." * click* "Bartleby the Scrivener? What, not many Melville fans here, huh?"
Archer: "God, I SAID the cap slips off the poison pen for no reason, didn't I?!" Cyril: "I know, I know, but I just assumed that if anything bad happened it-it would've been-" Archer: "No, do NOT say the Chekhov gun Cyril! THAT, sir, is a facile argument!" Woodhouse: "Also woefully esoteric."
Archer also tends to make obscure psychology jokes. At one point Lana tells Cyril that his sexual addiction is not a real thing. Cyril responds "Just wait until the new DSM comes out."
In the second Strawberry Shortcake special, The Purple Pieman tries to enter the bake off in "Big Apple City" by making "kohrabi" cookies. "Kohlrabi" is a type of cabbage, hence why they taste so awful.
Quite a few of the details of Avatar: The Last Airbender would go completely over the head of anyone not familiar with written Chinese, or various intricate details of Asian cultures and history. They are detailed exquisitely here.
There's more linguistic jokes: in the episode Bitter Work, Sokka promises to give up meat and sarcasm. The word sarcasm comes from the Greek word for meat/flesh: sarx. Not to mention the title itself is a possible translation of "kung fu".
In the Book 3 finale of The Legend of Korra, Korra is poisoned by a metallic substance. Some might recognize the only metal that is liquid in nature: mercury.
The Boondocks is rarely a subtle show. Some viewers might have missed the Wunclers parodying Bush's family and administration, since their actions work as jokes on their own and it's never stated outright. The comics became famous almost entirely for the author's stance on them, though. And "Wuncler" sounds exactly the same as "Once-ler", a man who—in Dr. Seuss's "The Lorax"—used business to drive out everything that was natural to the land and make it a desolate wasteland. Take notice in the episode where Mr. Wuncler tricks Robert Freeman into opening a soul food restaurant which drives the crime rate up so that he can buy the park next to it.
My Gym Partner's a Monkey contains a surprising number, usually delivered by Windsor the gorilla, such as when he explains what would otherwise be a fairly lame gag about an owl answering "Who?" to every question asked of it is, in fact, an illustration of the Socratic dialogue.
Dexter's Laboratory - Dexter's Joke. It's about the professor's wife being a pain.Explanation Salicylic acids are used to make pain relievers, in particular aspirin (acetylsalicylic acid).
One comment on the video explains:
"I feel like there can be two meanings:
1) As many commenters have stated, hydroxyl ions are abbreviated as OH- or, in this case, HO-. So, the punchline will read: "That's no HO, that's my wife!"
2) He talks about the professor trying to "liberate" negatively charged hydroxyl ions (HO-). After the punchline, it could mean that the professor is trying to figure out how to "liberate" himself from his wife.
Either way, it is a GREAT joke, which definitely went over my head when I was younger!"
In the X-Men: Evolution episode "Middleverse", one of the devices created by mutant Forge is said to run on CP/M, a pre-DOS computer OS.
Batman: The Animated Series is *thick* with these, but one standout example is "Carl Rossum," a brilliant cyberneticist named for the author Karel Čapek and the main character of his best known play, R.U.R., a.k.a. Rossum's Universal Robots.
In Fireman Sam, the Welsh wannabe rock star being named Elvis Cridlington is funny for obvious reasons. It's even funnier if you know the popular but discredited theory that Elvis's name is of Welsh origin (Elfys Preseli).
Phineas and Ferb: In The Movie, Candace wonders out loud why the mysterious force of the universe helps her brothers so much. Buford says, "Well, why don't you ask it, Kierkegaard?" He gets weird looks from the others, to which he responds, "Existentialist trading cards. It came with the gum."
Baljeet: Would you like to trade two Sartre for a Nietzsche?
In the episode where they're at the endangered species benefit...
Scientist 1: I bet I'll have more species named after me than you. Care to make a wager?
Scientist 2: No.
Scientist 1: Why not?
Scientist 2: Because your last name is "Pithecus".
The song writing staff are clearly familiar with Marxist economic theory, because they keep referencing it.
Doofensmirtz: And at the end of the day, there's more for me/'cause everyone else is the proletariat/ and baby I'm the bourgeoisie- Look it up, Joe!
Heck, half of the humor on Phineas and Ferb is this.
The goofy astronauts in Tom and Jerry Blast Off To Mars spout an extensive Joseph Campbell quote while wondering if humanity is alone in the universe:
Astronaut 1: The universe? An inconceivable immensity of galaxies, clusters of galaxies, and clusters of clusters of galaxies, speeding apart into expanding distance. And humanity? A kind of recently developed scurf on the epidermis of one of the lesser satellites of a minor star in the outer arm of an average galaxy, amidst one of the lesser clusters among the thousands, catapulting apart, which took form some fifteen billion years ago as a consequence of an inconceivable preternatural event.
In the Doug episode "Doug's Brainy Buddy", Doug has a hard time believing that Skeeter could be a genius after the latter gets a perfect score on an intelligence test... until he notices Skeeter's collection of books includes Immanuel Kant's A Critique of Pure Reason, among other heavy science and philosophy texts.
In one episode of MAD, a young time traveler knocks out his father with a "Titor" brand aluminum bat. John Titor was the name used by someone who posted on various internet forums claiming to be a time traveler.
In "Daddy's Little Monster", while Jake is recording Finn's fight with the amulet-possessed Marceline, Finn gets thrown at Jake and Jake shouts "Ow, my hippocampus!" Present!Jake says "That explains why we got amnesia", and he's right: the hippocampus is the part of the brain that supports formation of long-term memory.
The objects used to summon Bella Noche in "Betty" are a sword, a orb, a staff, and a goblet. These represent the suits in Minor Arcana Tarot (Swords, Pentacles, Wands, and Cups).
"Chip Off The Old Smurfs" from The Smurfs. Handy Smurf and Painter Smurf are arguing over Baby Smurf's future when Poet Smurf walks in to find Baby Smurf singing a song to himself, in baby talk, and rhyming the last syllable as he sings. Poet's response? "Why, listen to that, free verse!"
In "Helga on the Couch", from Hey Arnold!, one of the paintings on psychiatrist Dr. Bliss's wall is by Andrew Wyeth. Wyeth was involved in a complex, semi-secret relationship with a model named Helga, whom the show's character in fact somewhat resembles.
The Schoolhouse Rock song "Unpack Your Adjectives" features a part where the protagonist labels two characters "dumb" and "brainy", initially incorrectly due to intelligence stereotypes like Fat Idiot, Dumb Muscle and Smart People Wear Glasses. The bulky guy proves he's actually the brainy one by rattling off a definite integral, a type of formula people wouldn't see until after several weeks of calculus. It's completely accurate, right down to simplifying the answer. What makes this better is that it's a Grammar Rock song and this series' main contributions to mathematical knowledge are the much more rudimentary multiplication tables. Doubles as a Freeze-Frame Bonus.
The ponies give Princess Luna a flower necklace as a sign of forgiveness. The flowers are red and white roses, together, symbolizing reconciliation within the royal family, just as the red and white rose of the Tudor house in real life symbolized the reconciliation between Lancaster and York at the end of the War of the Roses.
In "The Best Night Ever", Spike briefly mentions the princess's golden apple tree. In Norse mythology, the golden apples are the source of the gods' immortality and perpetual youth.
"Luna Eclipsed" has one that doubles as a Stealth Pun: Twilight Sparkle dresses for Nightmare Night as "Star Swirl the Bearded", a unicorn wizard from ancient times who was "father of the amniomorphic spell", according to Twilight. "Amniomorphic" means "bowl-shaped" in Greek, which means Star Swirl was a bearded shaper of bowls, or a hairy potter. In addition, "amnion" is the term for the membrane that forms around the fetus of reptiles, birds, and mammals, meaning this may also be a Call-Back to the spell Twilight cast in "Cutie Mark Chronicles" to hatch Spike's egg. This episode also has a far more subtle case when Princess Luna doesn't understand what "fun" means. It's not the concept of fun that baffles her, it's the word itself. The word "fun" is less than 1000 years old, which is how long Luna spent banished to the moon.
In "The Cutie Pox", Apple Bloom all of a sudden gets a cutie mark shaped like a Fleur de Lis. Immediately, she begins speaking in French. The average American child watching the show is unlikely to be aware of the connection between a Fleur de Lis and the French language. And of course, if the viewer does not speak French, he or she will not know what Apple Bloom is saying. And in the French dub, she speaks in old, archaic French.
In "Griffon the Brush Off", we're introduced to bully character Gilda, a griffin who picks on the protagonists. What kids watching the show probably don't know is that in the original myths, griffins supposedly ate horses.
In the episode "Bridle Gossip", Zecora shows a number of strange habits or possessions that cause the ponies to conclude that she's evil. All of these are explained away in the episode as actually being entirely innocuous... except for her habit of pawing at the ground and digging small holes. This is something zebras actually do to find water — by pawing at the ground of dry river beds and the like, they can draw out water that's seeped into the ground. Also, while zebras scrape their hooves on the ground to find water, in horses and ponies (in-show and in real life), it is a display of aggression.
Big Macintosh's Discorded form where he acts like a dog that burrows in the ground makes little sense to most people who assume that's the idea given who's responsible. Anyone from the central United States or Canada will instantly recognize it as a both a pun and a reference to Prairie Dogs: small burrowing creatures that are a nuisance to farmers.
A lot of the creatures in the show take inspiration from actual mythological creatures. Most everyone knows about the Hydra and Cerberus, but Orthrus the two-headed dog, Jackalopes, and Windigos are much lesser known references.
Cerberus is the subject of one as well. Him being friendly to the ponies after a tummy rub may seem like nothing more than a joke, it's actually a reference to the fact that Cerberus, while aggressive, could easily be tamed by giving him a treat (small cakes in the original myth).
In "It's About Time", Twilight Sparkle is seen working at a chalkboard full of equations while trying to figure out the supposed disaster that her future self traveled through time to warn her is due to happen by Tuesday morning, and how she might prevent it. The equations in question describe the effects of time dilationnote it's only the base formula, however, not an actual application of it - note how all variables are in their literal forms.
In "A Canterlot Wedding - Part 1", we get a musical foreshadowing bonus in the form of "This Day Aria", as explained here and verified here. Long story short: a certain sequence of tones ending in a major chord is called an "Authentic Cadence". If it instead ends in a minor chord, it's called a "Deceptive Cadence".
Similar to "It's About Time", in the episode "Slice of Life", the equations that Doctor Hooves imagines when he considers bowling are legitimate physics formulae.
At the end of "School Raze", we see a female Royal Guard for the first time in the series, being one of the ones to escort the arrested Cozy Glow. This is a nod to how real life militaries will have a female soldier escort, search, and arrest a female or underage detainee whenever possible to prevent Culture Clashes or certain accusations.
In an episode of South Park, Kyle will die without a kidney transplant and Cartman is the only match. When asked to help out, Cartman sings the word "No!" over and over again...to the tune of a song titled "Comedy Tonight".note Cartman is, of course, missing the obvious here. If he is the only match for Kyle, then Kyle is the only match for him.
"Ginger Cow" makes more sense if you know what a Red Heifer is.
Rick and Morty features this trope mixed with Getting Crap Past the Radar. In "Rick Potion #9", the characters Jerry and Beth have a strained marriage which gets a lot better after the world is transformed into a post-apocalyptic hellscape by Rick's antics. Jerry, usually the Butt-Monkey, turns into a Crouching Moron, Hidden Badass as he rampages through horrid monsters. Beth helps him with a shotgun. Jerry says he wishes his penis was the shotgun, to which Beth replies that if it were, he could call her Ernest Hemingwaynote Hemingway Ate His Gun with a shotgun, an act that is colloquially sometimes called kissing a shotgun or something more crude along those lines. She's offering to eat his gun, as it were.Jerry doesn't get it - and says as much.
Kids watching might think the concept of the Beagle Boys is just someone being silly, the idea of a gang headed by an evil middle-aged lady, complete with parasol and purse, whom the gangsters affectionately call "Ma" and yet be skilled and organized enough to terrorize the populace wherever they go. However, there really was such a gang with this reputation: The Barker-Karpis Gang was the scourge of the American Midwest during The '30s, briefly notorious enough to be the FBI's top priority, and a popular rumor during the time was that the real leader was Kate "Ma" Barker. Though it's now known as false (the leader was her son Fred), Ma Barker frequently traveled with Fred and knew full well what her son was up to.
Gladstone Gander hums "Luck Be a Lady" just before he is brainwashed into helping Magica and has his luck turned bad. While it works just based on the title and Gladstone's Born Luckiness, viewers who know the song will get more out of the joke, given that "Luck Be a Lady" is actually talking about how unreliable luck is the lyrics amount to, "Luck, please be a lady tonight, and don't skip out on me and leave me to hang, because you do that a lot."
In the Season 1 finale, Gyro force-feeds a "Barksian modulator" to Donald so that everyone can understand him for once. The device is named for Carl Barks, one of the two biggest contributors to the entire Disney Ducks universe. (The other was Don Rosa.)
The season two premiere features Scrooge and the kids exploring "The Lost City of Cibola", a nod to the Carl Barks story "The Seven Cities of Cibola", which has been cited as a major inspiration for Raiders of the Lost Ark and the rest of the Indiana Jones movies. Meaning Raiders of the Lost Parody had finally come full circle.
Another obscure reference is the revelation that Flintheart Glomgold is actually a South African named "Duke Baloney" and his Scottish persona is just an act. Glomgold was in fact originally South African (though still of Scottish descent) in the original comics before The Apartheid Era prompted the original DuckTales to change him to just being Scottish and the comics to avoid mentioning his heritage altogether. As for "Duke Baloney", it's a reference to the Duke of Baloni, a one-off character said to be the second richest duck in the world (before Glomgold was introduced) who Donald impersonated in the Carl Barks story "Turkey With All the Schemings".
On Llama Llama, Euclid is a very intellectual type and is named after Euclid of Alexandria who is often referred to as the "founder of geometry." In "Snow Show," Euclid makes as his snow sculpture an ancient Roman coliseum model, measured perfectly, that Llama Llama says looks great from all sides.