One episode features one huge mythology gag. It's a bunch of kids telling their "Rashomon"-Style stories about the Batman, one being 60's campy, one being Miller's Dark Knight, and at the crowning moment of funny they stumble upon a very feminine boy stroking a feather boa saying, "I love Batman, that rubber costume, the car that can drive up walls," and another kid remarks something along the lines of, "oh please give me a break Joel," an obvious reference to Joel Schumacher and his Batman movies.
And another one was all-but an homage to the 1960s "campy" Batman starring Adam West... who, appropriately, voiced himself as "The Gray Ghost" and his actor.
In X-Men: Evolution, one episode features the theme song from the original X-Men animated show remixed as a sort of tropical poolside jazz piece.
Also, in the episode "Under Lock and Key", the five members of the original X-Men team from the '60s (Cyclops, Jean Grey, Beast, Angel, and Iceman) are sent on a mission together.
Wolverine's second costume was the same one he wears in the Ultimate continuity.
In one episode, Kitty is shown hugging a purple dragon toy before bed, referring to her friend/pet Lockheed in the comics.
Teen Titans, while not as mythos-heavy as the DCAU (being separate from it), has its share of Mythology Gags as well.
In "Apprentice", Slade forces Robin to become his apprentice, and then states that he'd eventually become like a father to him. Robin's response? "I already have a father," while the camera pans up to a group of bats flying away, complete with music that sounds awfully like the B:TAS opening.
One of Beast Boy's imagine spots has him jumping out of an old comic cover while a banner proclaims him the "new sensation of 1963." 1963 being the year Beast Boy first appeared.
Even better, Beast Boy was dressed up as Robin at the time. The composition of the shot (Beast-Boy-as-Robin bursting through a screen held by Starfire/Batman) is an homage to the cover of Detective Comics #38, Robin's debut. Only he was the new sensation of 1940.
The big fight scene for the episode takes place around a large neon sign, toppling an A and a Y, until the final wide angle shows what's left to read 'W_ _NE Enterprises'.
When a never-revealed mystery person takes up Robin's old Red X costume, Beast Boy speculates on who it could be—his board-o'-theories includes Jason Todd, an ex-Robin who'd similarly appropriated the identity Red Hood in the comics.
Another suspect is "Robin's Long-Lost Brother". Robin has an older brother who died along with his parents in Batman Forever. The brother shown on the board also visually resembles Scott Menville, Robin's voice actor.
In one episode they meet a magical kid from another dimension who is a huge fan of Robin. His name is Nosyarg Kcid. They decide to call him Larry instead.
Larry is an Expy of Bat-Mite, a similar Batman character now removed from comic book continuity...maybe.
In the episode where Mumbo captures the Titans and turns all but Beast Boy into animals, Starfire is turned into a cat. The original comic established that Starfire's people evolved from cats.
In "Lightspeed", one of these pops up as a Freeze-Frame Bonus - when Mammoth comes out of a store, the candy bar he's carrying is a Lightspeed Energy Bar, the same brand that Flash shilled for in an episode of Justice League. Fittingly enough, the bar is stolen out of Mammoth's hand by Kid Flash, who's being voiced by the DCAU Flash's voice actor Michael Rosenbaum.
One DC Nation short has the Titans, thanks to Mad Mod's time machine (Built to resemble a British phone booth) has them transported to various time periods. When they reach the 80s, they're dressed like their comic counterparts.
The 90s part also features a few shout-outs to the "New Titans" era (1991-1996): Raven as a red-skinned demon, Cyborg with bulkier armor, Beast Boy with a mullet, and Starfire wearing the armor that Mirage used while impersonating her.
In the episode "Secret Origins" April O'Neil poses as a TV reporter to infiltrate a building, wearing a very familiar yellow jumpsuit; when she tries to "interview" the soldier supervising the blockade around the Utrom building (it's complicated), she explains that she's from "Channel 9 News *broken tag on jumpsuit flips down* er, Channel 6 News". Later, once the smoke clears, Donatello says April would make a good reporter, to which she replied "In another lifetime, maybe." These are all references to the previous Ninja Turtles cartoon, where April was a reporter for Channel 6 News.
The van is kept in a warehouse on "the corner of Eastman and Laird".
Turtles Forever, full stop! Not only do we have a crossover between the 2003 and 80s series, but a view of the multiverse shows pretty much every other continuity ever.
In the same episode, as the alien Utroms escape the under-siege T.C.R.I. building, one makes a complaint, to which the other says "Oh, shut up, Krang."
Note that both Krang and the Utroms were based on aliens that originally appeared in the original comic book series by Eastman and Laird.
A season four episode features anthropomorphic rhino Gennosuke, exploring NYC when he becomes taken with a muscular punk's outfit. One "shopping" trip later, he is seen wearing the outfit: a tight yellow wifebeater, cargo pants, and an ammo belt strapped across his gut—the outfit anthropomorphic rhino Rocksteady wore in the original TMNT series. To complete the look, Casey Jones slaps a helmet on him as he leads the rhino away.
In addition, that same episode featured a villain from the same dimension as Gennosuke and his friend Usagi, an enemy who was an anthropomorphic warthog. While said character doesn't look anything like Bebop, it could hardly be a coincidence.
Leatherhead's lair is taken from the turtles' second lair in the movie series.
The other short, "Jesus vs. Santa", is the one the boys are working on in "A Very Crappy Christmas".
In the episode "The Passion of the Jew", when Stan asks for a refund over the phone, he says that he'll get his money back like he did for BASEketball, a movie that Matt Stone and Trey Parker both starred in.
Also counts as Self-Deprecation, as almost immediately afterwards, he and Kenny both agree that is was a terrible movie.
In Scooby-Doo on Zombie Island, there's a scene where Fred is going through his clothes while dressing... and comes across a bright orange ascot. "Nah", he decides. Animated versions of Fred haven't touched the ascot since the late 1990s.
Velma: An ancient ghost coming back after a hundred years to get revenge? Yeah right, who'd believe that?
Scooby-Doo and the Cyber Chase has the whole last section as a hurricane of references to the series, such as the outdated clothing, the monsters being fake, and obviously the returning monsters from the original series.
Beyond that, there have been cameos by other Hanna-Barbera characters. Pebbles and Bamm-Bamm appear as beach-goers in one episode, while Suzie Chan makes several non-speaking cameos as a student at the Mystery Inc. gang's high school. Some of the more significant ones, having more serious plot relevance, include the Blue Falcon and the cast of Jonny Quest in "Heart of Evil," and the villain of that episode was recurring Jonny Quest antagonist Dr. Zin.
The villain Alice May looks almost exactly like Gwen Stacy from Spider-Man, right down to her clothing and color palette. She's even shown wearing a spider pattern dress during her capture.
Near the end of "Howl of the Fright Hound", some animal control officers are wheeling away a bear wearing a familiar hat and necktie.
In the Be Cool, Scooby-Doo! episode "Me, Myself, and A.I.", the gang is being chased by a robot through a virtual reality simulator. At one point, the gang becomes their original designs from Scooby-Doo, Where Are You!, while the robot becomes Charlie from "Foul Play in Funland".
In the original 1965 version of Secret Squirrel, the title character spoke with a lisp (he was voiced by Mel Blanc, doing a voice very similar to Sylvester the cat). In the episode "Goldflipper" of the 90's revival, Super Secret Secret Squirrel, Morocco Mole starts lisping after losing his gold tooth, and Secret affects a lisp too in order to mock him, making him sound more like his original counterpart.
Bumblebee first appears next to a yellow Volkswagon Beetle, his G1 altmode.
Optimus Prime says "One shall stand, one shall fall", lifted from similar circumstances in the 1986 animated movie. In fact, several of Prime's catch phrases from the G1 series were incorporated, also including "Freedom is the right of all sentient beings."
The series actually begins with footage from the original 80s show (presented in the episode as history tapes)
In the first episode, when the Autobots are first attacked, Bumblebee says Rattrap's Catch-Phrase "We're all gonna die, aren't we?"
He later once called Optimus "Big Bot", like Cheetor did for Primal.
When Bumblebee notes how weird it is that Prowl's vehicle form is a motorcycle without a rider, he suddenly makes a hologram rider like the one from the live-action movie (AKA Mustache Man).
The new version of Soundwave has eyes that change between the yellow of the original toy to the red of the G1 cartoon, and was first seen in a box resembling his G1 alt mode, and at one point he develops a shoulder cannon, and the fragment of him left at the end is based on the MP3 player Soundwave.
There's a double gag in the second season's "Garbage In, Garbage Out" with "I am Wreck-Gar! I dare to be stupid!": it referenced not only Wreck-Gar's Animated voice actor, Weird Al (who sang "Dare To Be Stupid"), but also the appearance of the original Wreck-Gar in the 80s animated movie (where the same song was played). In the same episode, Wreck-Gar throws the motorcycle altmode of his G1 namesake at Bumblebee. And, yet again in the same episode, he mistakes one of Lugnut's weapons for "the universal greeting", reaching for it as he says "Bah weep graaagnah wheep ni ni bong", another reference to his introduction in the G1 movie. At this point, it might be fair to just call the entire character a giant mythology gag.
In the same episode, Ratchet gives a ride to a married couple named Spike and Carly, who greatly resemble the late G1/Headmasters characters of the same names. They originally appeared in the background of the first episode, along with their son Daniel who's made a few recurrences himself.
Sari has a robot dog named Sparkplug, evidently named after the G1 character (Spike's father). A construction worker who strongly resembles him appears in a few episodes.
For Halloween, Sari dresses up as G1 Optimus Prime. Well, okay, she dressed up as Animated Optimus, and ended up looking exactly like G1 Prime.
When Megatron is trying to create a new body, he says he needs a substance called 'Destronium'; this is probably a reference to the Japanese G1 continuity, in which the Decepticons were called Destrons (and paralleling Cybertronium, as the Autobots were called Cybertrons in Japanese).
When the Constructicons are brought to life, they appear in the vicinity of a crane that resembles the alt mode of Hook, a G1 Constructicon. This is a whole season after they pulled a fast one by earlier showing a group of automated construction vehicles/mining equipment in G1 Constructicon colors, which are never seen again (Though Mixmaster and Scrapper do eventually get G1-style paint jobs after officially becoming Decepticons).
In the last episode of the first season, the Autobots' ship is partially buried in a volcano, similar to what happened to the Ark at the start of G1.
Swindle mentions in passing that he has had dealings with the Vok. The Vok were incredibly powerful aliens that were the secondary antagonists in Beast Wars. Later, in the season 3 episode "Decepticon Air", he mentions having dealt with the Quintessons, from the original movie and later seasons of the G1 cartoon.
And then there's a human villain called Headmaster, with a suit of Powered Armor that works in a very similar manner to the Headmaster suits from the aborted fourth series of Transformers: Generation 1.
Starscream's clones (except the female one) all have color schemes copied from the other G1 Seekers — characters who were essentially Palette Swaps of Starscream or became similar F-15 jets.
The Sycophant: Sunstorm The Coward: Skywarp The Liar: Ramjet The Egomaniac: Thundercracker The Female: Japanese Transformer Overlord (according to Word of God); also resembles Generation 2 Ramjet. Officially named Slipstream.
Susan Blu, voice of the original Arcee, was the voice director for Animated, and got to briefly reprise her role in a flashback.
The Decepticon team introduced in season 3 is named "Team Chaar", after the planet the Decepticons moved to after finally being expelled from Cybertron after The Movie in G1. (Aptly enough, the Autobot team that fights Team Chaar is headed by Rodimus Prime, who didn't exist until after the movie.) It's unknown if Animated has its own planet Chaar, however.
In the same episode, Waspinator is seen pulling himself back together while commenting "Waspinator has planzzz...", both trademarks of the oft-exploded original Waspinator in Beast Wars. However, while the original did both these things in a cute or humorous manner, Animated made them seem a lot creepier.
In "Human Error, Part 2", Scrapper has a Dinobot pet and named him Snarl. When Sari asks, Scrapper answers, "Well, I was going to name him Slag, but I think he took it as an insult." Probably a double callback, as the original character was named Slag, and this was both a curse in Cybertronian and, in the UK, a lesser-known word for "slut," meaning the toy was not sold there much and necessitating a name change.
As of "Decepticon Air," Ramjet (Liarscream) and Sunstorm (Sycoscream) have shiny new helmets courtesy of Swindle — helmets that just so happen to match the heads of their G1 predecessors.
In "Endgame, Part 1", the Omega Clones resemble the Dark Guardians, the giant robots that the Quintessons used in Generation 1 to keep the ancestors of the Cybertronians in line. Fitting, seeing as how G1 Omega Supreme was a surviving Dark Guardian reprogrammed and made sentient as an Autobot.
The mysterious alien Alpha Q is based on the G1 Quintessons, although he only has three faces (G1 Quintessons had five). In fact, in the comic, his full name is Alpha Quintesson.
Rodimus' "travelling to the future" in his backstory mirrors his departure with Kup and Blurr to find a new homeworld during Transformers Headmasters.
Shockblast dies by being stomped by Unicron, which was implied to happen to his G1 counterpart in the movie, although the scene was cut short.
Ironhide's mid-season redeco is based on G1 Hound, and his Japanese name is Roadbuster, after another G1 Autobot with a jeep alt-mode.
Bulkhead resembles G1 Springer, albeit without the car altmode, and is named Sprung in the Japanese version.
Downshift is designed after G1 Wheeljack, but had to be renamed since that name was already taken by an Autobot-turned-Decepticon in Armada.
Transformers: Shattered Glass can get downright labyrinthine. For instance, in Shattered Expectations, Dirge shows up in a body based on Games of Deception Dirge, in Beast Wars II Thrust's colors, in a pose mimicking Ramjet in Transformers: Generation 2, bursting from a Pretender Shell based on Descent into Evil Dirge, in Chromia's colors, in a pose mimicking Octopunch from Generation 2. And this is ONE CHARACTER ON A SPLASH PAGE.
After Megatron is gone at the end of the Darkness RisingFive Part Pilot, Starscream makes himself the new leader using the monicker of "Emperor of Destruction", the same one used by every Decepticon leader in Japanese series.
Arcee admires Bumblebee's new paint scheme after they go into hiding: black with yellow highlights instead of yellow with black highlights. She comments that she couldn't do that, since she would be mostly pink, which was her G1 scheme.
Soundwave is The Silent Bob, able to carry on a complete conversation despite never speaking or even having a face. He can speak, but he only does so once, a straight call back to G1: "Soundwave: superior. Autobots: inferior."
The Mini-Con ship is buried in a mountain like the Ark in G1.
Hot Shot initially resembles Bumblebee, but for his Mid-Season Upgrade he gets the paint job of Hot Rod/Rodimus Prime, who appears as a separate character in the aforementioned Energon.
Megatron's Mini-Con is named Leader-1, after the leader of the Guardians in Tonka's Go-Bots rival toyline.
Starscream's Powerlinx redeco sports G1 Thundercracker's colors, and he lampshades this with "I look like...Thundercracker!". He also has a toyline-exclusive retool as Skywarp.
In the episode "Portent", a dead Autobot resembling G1 Jazz is embedded inside Unicron. Maybe he didn't make it out during the movie after all.
In "Cramp", Starscream is disintegrated by Unicron in a manner similar to his G1 counterpart.
The Simpsons episode "Lisa's Sax": "Tracey Ullman was entertaining America with songs, sketches, and crudely drawn filler material." That filler being the early Simpsons shorts.
In "Treehouse of Horror XIII", Homer makes clones of himself. One of them resembles his old design from The Tracey Ullman Show, with the same voice and catchphrase (the 'Frosty Chocolate Milkshakes' line).
Another episode has the family recreating their family photos, including one that says "Happy 1987." Bart, Homer, and Lisa look like their Tracey Ullman counterparts before shaking their heads and reverting back to normal.
In another episode, the family is watching FOX's latest round of animated programming. Homer comments that animated shows are great for networks "because they don't have to pay the actors squat!" Flanders then walks by the window, stating that "they can replace them and no one can tell the diddly-ifference!" in an obviously-different voice (Karl Weidergott rather than the usual Harry Shearer). At the time, the Simpsons' cast had been engaged in very bitter salary disputes with senior management, which included threats of firing all the active cast and hiring sound-alikes.
As in many animated shows, the characters have frequently made reference to their unchanging wardrobes.
In "Pokey Mom", Homer, after taunting a bull at a rodeo by drawing attention to Lisa and her red dress, turns to Bart for "some calming blue", then exclaiming "where's your blue shirt?", to which Bart responds, "I don't have a blue shirt" - referencing the blue shirt Bart tends to wear in knockoff merchandise.
In "Itchy and Scratchy the Movie", Lisa tells Bart that the eponymous movie had cameos by Dustin Hoffman and Michael Jackson: "They didn't use their real names, but you could tell it was them!" Both appeared in classic episodes of The Simpsons under pseudonyms.
In "Das Bus" (aired in early 1998), Bart tries to entertain his classmates by singing "Do the Bartman" (a novelty hit single his character had in the early 1990s). Ralph's reaction: "That is so 1991."
Another episode "Sweets and Sour Marge" has Chief Wiggum attempting to burn Butterfinger snacks, but as he puts it "Even the fire won't take them". Bart Simpson was the mascot for this brand and made TV commercials to endorse the product.
In Code Lyoko Season 4, the large room in Sector 5 that houses the Skidbladnir is called "Garage Skid" by Odd. This is a reference to Garage Kids, a short film by the creators of the show that was a test pilot for the series.
On SpongeBob SquarePants, Krabs refers to SpongeBob as, "Spongeboy, me Bob!" rather than "SpongeBob, me boy!" in the episode "Squeaky Boots". On a later episode, "Frankendoodle", the titular doodle is first named Doodleboy, then later is called DoodleBob. These are references to SpongeBob's original name, Spongeboy, which was changed for legal reasons.
In the episode "Patrick! The Game," Patrick makes a game called "Tic-Tac," a shorter version of Tic-Tac-Toe. An issue of Nickelodeon Magazine featured this game long before the episode that featured it. With the exact same character, nonetheless!
The Batman features a bunch of references to classic Batman comics.
The future-based episode "Artifacts" has a scene where an aged Batman steps out of his Batmobile to fight Mr. Freeze. Freeze greets him with the words: "The Dark Knight returns!"
Alfred also resembles his counterpart from the story, being a lot older and needing to use a cane to walk around.
There's also a tank-like Batmobile ala TDKR.
In the same episode, Robin and Batgirl assume their present-day comic identities of Nightwing and Oracle respectively.
Ellen Yin seemed to be based off on Ellen Yindel from The Dark Knight Returns, and is hinted in "Artifacts" to have replaced Gordon as Commissioner like Yindel did in TDKR.
In the same episode during some speculation, Robin and Batgirl are referred to respectively as Red Robin and Batwoman.
Mr. Freeze suffered a similar, though less severe, deterioration as his Batman: The Animated Series incarnation and hence has replaced his legs with robotic spider legs.
In the episode "Team Penguin", the other members of Cobblepot's Legion of Doom keep suggesting different names for the group. Ragdoll comes up with "Villains United", the title of the book that introduced the Secret Six.
When the opening sequence changes to showcase Robin, he appears bursting through a circular a screen. As mentioned in the Teen Titans section, this is a reference to the cover and title page of Detective Comics #38, the 1940 issue he debuted in.
An example from a different medium: In the episode "JTV", Joker takes over Gotham's TV channels. The broadcast includes a couple of references to the 1960s Batman series, with Joker delivering the narration "Same Joker crime, same Joker channel!" and displaying the battle between Batman and Joker's henchmen with cartoon "BIFF", "POW", "SPLAT" overlays.
Kim Possible alluded to how the show was going to end in the episode "Bad Boy", as Kim and Ron are watching their favorite prime-time soap, "Agony County", and complaining about the status of one couple. A few episodes later, "So the Drama" ended with Kim and Ron getting together, and was supposed to be the Grand Finale, until the producers decided to bring the show back.
Ron: Oh please, are they still teasing that Charity and Dannie are gonna get together?
Kim: Like that's ever gonna happen. It would end the series.
Hey Arnold! features a few nods to Craig Bartlett's original Arnold comics.
In the episode "Monkey Business" Helga gives away her sousaphone when she thinks she's gonna die from monkeynucleosis. In the original Arnold claymation shorts, she played a sousaphone in Arnold's band.
In the episode "Out of the Past", Ra's Al Ghul attempts to use the Lazarus Pit to restore Bruce's youth before putting his mind in his body. He mentions that he will take over Bruce' empire by claiming to be the long-lost son of Bruce and Talia, which is a reference to Batman: Son of the Demon where Bruce and Talia conceive a child (who, since the end of the series, was reintroduced to the comics as Damian Wayne).
In the Batman musical Bruce and Terry see, the Musical Batman says "Criminals are a superstitious, cowardly lot." a line from a Golden Age-era comic. Also, the musical version of Catwoman is anthropomorphic a la Cats, which did happen in this continuity that one time. Finally, Musical Robin is played by a woman and somewhat resembles Carrie Kelley.
"Heroes" had three superheroes using the name "the Terrific Trio", which was originally used in the campy 60's series, which was the Dynamic Duo, plus Batgirl.
This rather obvious one occurs in "The Call" when Terry is fleeing from Superman using the flying Batmobile:
Terry: What's the top speed on this thing?
Bruce: Mach 3.
Batman: Is that faster than a speeding bullet?
In the series finale of As Told by Ginger, she shows all of her friends the book she's written about her life. The picture of her on the book is the original character design from the unaired pilot.
Danger Mouse: In "Penfold Transformed", Greenback dresses Stiletto in a Penfold costume to counter Dr. Crumhorn's Penfold robot (planted with DM to replace the kidnapped real Penfold). Stiletto makes a reference to Greenback's ill-fated Penfold duplicator (or magnetic molecular molder) from the earlier episode "Tiptoe Through the Penfolds."
In an episode of Count Duckula, the count is wearing a nightshirt with Danger Mouse's "DM" logo. Duckula first appeared on Danger Mouse as an antagonist.
In their early days, Hanna-Barbera would make outright stars of characters either referenced earlier or appearing earlier. Quick Draw McGraw's name was first seen on a note on a door in a 1957 episode of The Ruff & Reddy Show (the studio's first series), Snagglepuss was an antagonist on the Quick Draw show, Ricochet Rabbit (from The Magilla Gorilla Show) first appeared as an antagonist on Touchè Turtle, and the Ant Hill Mob was first seen as a gang on insect bikers in an episode of Atom Ant.
The Problem Solverz references its [adult swim] pilot Neon Knome in some episodes. Kevin, the magic cup, can be seen in Horace's room, and the pictures on the wall are screenshots from the pilot. Roba also has a collection of Narrator dolls, and the giant Rollerblade appears in a few backgrounds. In "Hamburger Cavez", Roba unrolls his long sleeping bag the same way he did in Neon Knome.
In the Halloween level of the Garfield game Garfield's Defense Force, Lanolin's costume resembles her Wicked Witch of the Wool outfit from the Garfield and Friends episode "The Ugly Duckling", minus the ruby slippers.
In the sequel to that game, Wade is wearing Roy's police hat from "Wanted: Wade".
"Hot Air" features a Who Is Driving? joke about Goofy, where he honestly answers he is while obviously not, just like in the famous short, "Mickey's Trailer."
The How-To Narrator who appears several times when Goofy is in focus, much like in Goofy's classic how-to shorts.
In "Close Encounters of the Weird Mime," Goofy's mime instructor holds up cue cards with pictures. When it comes to "duck", the picture is of Donald Duck.
In A Goofy Movie, in addition to Max having a Mickey Mouse phone and Mickey and Donald making brief cameos, when Goofy says he's taking a trip with his "best buddy", Max's first thought is that it's Donald.
In Godzilla: The Series, the H.E.A.T. team went to investigate a string of disappearances in Japan. Naturally, GodzillaJr. followed them there. After swimming across the Pacific Ocean, a Japanese girl in a passenger plane spotted him arriving at Japan.
Girl: Mommy look! It's Gojira!
Mother: Don't be ridiculous; what would Gojira be doing in Japan?
The 2015 revival of Inspector Gadget has a couple so far observed from the leaked intro and a still image. The new opening contains some scenes from the original cartoon's opening, such as Chief Quimby having the door shut on him before his message explodes and Gadget handcuffing a fake Dr. Claw arm to find a bomb that makes him become the "I" in the show's title when it explodes. One of the leaked images for the show is of Gadget using his Gadget Copter, which bears some resemblance to how it appeared in the live-action Disney films.
In Barbie Spy Squad, the disguise selector contains many dresses and outfits from previous Barbie films, including Alexa's colorful dress, Nori's fairy dress, Corrinne and Kara's dresses and superhero outfits, and Clara's Nutcracker dress.
The vehicle Jeff Tracy was piloting when he disappeared was called TV-21, which was also the title of an Anthology Comic (originally TV Century 21) which ran from 1965 to 1971 and featured all the Supermarionation series.
Around 40:20 in the special Toot & Puddle: I'll Be Home for Christmas, a display board is shown in Toot and Puddle's house with a photo tacked to it showing Toot, Puddle and Opal as they appeared on the cover of the picture book Wish You Were Here.
The Beatles episode "I Don't Want To Spoil The Party" has a framed picture of Popeye on a Greenwich Village coffee house wall while "Tell Me What You See" has an appearance by Popeye's adopted ward Swee' Pea. King Features produced the Beatles' cartoon series and owns the Popeye characters.
Conversely, in Yellow Submarine (also produced by King Features), Old Fred and Ringo pass a hall of displays which has appearances by the Phantom and Mandrake the Magician, two King Features comic strip characters.
Although it exists in its own separate continuity, the Beetlejuice cartoon contains a number of nods to the film from which it was spun, such as having both Beetlejuice and Lydia singing "Day-O" in the pilot.
The episode "Applebuck Season" features Applejack, sleep-deprived from trying to clear all of Sweet Apple Acres by herself, acting in increasingly ditzy and klutzy ways. This is a nod to G1 Applejack, whose defining trait was her klutziness.
The episode "Dragon Quest" is almost a Whole Plot Reference to the G1 episode "Spike's Search". Both episodes feature Spike going on a journey to discover who he really is, only to find that the other dragons are bullies and end up staying with his friends.
In "The Ticket Master", Fluttershy hums the G1 theme tune as she cleans the library.
In "Sonic Rainboom", background pony Sassaflash makes an appearance, bearing a cutie mark that greatly resembles G1 Firefly's.
In "A Flurry of Emotions", the fairy tale Twilight reads to the sick foals, Gusty the Great, is about the heroic unicorn Gusty and her encounter with the treacherous Grogar. Gusty was one of the main characters of the original My Little Pony cartoon, and Grogar a major villain from the same show.
The opening episode of The Real Ghostbusters 6th season Janine, You've Changedlampshades the fact that from season 3 onwards Janine's visual design and voice changes several times.
Kanan's speeder-bike is described in supplementary materials as being a Joben-T85 produced by Zebulon Dak Speeder Corporation, referring back to the ending of the first arc of the Droids cartoon.
The pilot droid RX-24 from "Droids in Distress" was the pilot in the original Star Tours ride. They're both even voiced by Paul Ruebens.
In "Breaking Ranks", Kanan and Hera go after an Imperial kyber shipment, mention of which goes all the way back to a May 1975 synopsis of an early draft of A New Hope (although its own page]].first actual appearance was as the MacGuffin in Splinter of the Mind's Eye and it's now spelled as "kyber crystal").
The Imperial troop transports bear a strong resemblance to this 1979 toy◊, down to the prisoner cells mounted on the sides.
The title of the episode "Idiot's Array". In the old Expanded Universe an "Idiot's Array" is a winning hand in sabbac (and the episode establishes that that's still the case in the new continuity).
The Kanan vs Vader fight in "The Siege of Lothal" is noticeably slower and heavier than fights in the rest of the series, resembling the original Obi-Wan vs Vader fight in A New Hope.
"Shantipole" is the project name for Quarrie's B-Wing development program as well as the planet it takes it name from. In the old EU, Shantipole was the name of the asteroid base where the same B-Wing development program (called the Shantipole Project) was conducted by Admiral Ackbar.
The Hammerhead-class corvettes used by Princess Leia resembles the Endar Spire from Knights of the Old Republic. They even share the same class name, Hammerhead, with the difference being that the former are corvettes while the latter were cruisers.
The Empire's national anthem in "Empire Day" is an upbeat remix of the Imperial March.
Darth Vader's helmet design is reminiscent of Ralph McQuarrie's original concept, which featured a brow that made him look very sinister.
The outfit worn by the young Princess Leia is taken from unused concept art McQuarrie did of Leia for A New Hope.
The Lasat term for the Force, "The Ashla", was the proper name for the Light Side of the Force that George Lucas created for early script drafts. The Dark Side on the other hand was referred to as the Bogan, which the Bendu brings in Season 3.
Ahsoka states "There is always a bit of truth in legends", referencing the formerly Exiled from Continuity elements in the Legends continuity.
The Bendu's name is a reference to Lucas's idea of the Jedi-Bendu, who became the Jedi in the final product.
The Imperial Security droids in "The Wynkahthu Job" bear a strong resemblence to the Phase-II Dark Troopers from Dark Forces.
Kanan using the Force to launch a missile back into the imperial walker that fired it is a reference to The Force Unleashed II. The fact that he resembles Rahm Kota while doing it is a bonus.
The mid-season trailer for Season 3 has Maul confronting Obi-Wan Kenobi on Tatooine, like he did in the Old Wounds comic.
The code word to shut down the droids Thrawn spars with is "Rukh", the name of his Noghri bodyguard in the Legends continuity. He'd later appear in Season 4.
In the original Inspector Gadget episode "Focus on Gadget", Gadget gets his nose caught in an airlock door, which is a nod to the closing sequence of Don Adams' prior series Get Smart, where the last CONTROL HQ door closes on Maxwell Smart's nose when he attempts to shut it manually.
The Loud House: The season 3 episode "White Hare" shows the Loud Family as rabbits, with Lincoln's counterpart Warren having 25 sisters. This was what Chris Savino originally had in mind for the series before Nickelodeon convinced him to make the characters human.
The 7D: Grim and Hildy Gloom are named after the alternate name for Snow White's Evil Queen, Grimhilde.