Justice League is very fond of doing these. Examples include, but are not limited to:
- A page
of Superman allusions on the DCAU wiki. - In the first story arc, Superman suggests forming a team of heroes. The Flash responds, "What, you mean like a bunch of...Super Friends?"
- The story arc is titled "Secret Origins," itself referencing the title of the first Super Friends episode (Secret Origins of the Super Friends).
- In "The Great Brain Robbery", Flash (Michael Rosenbaum) and Lex Luthor (Clancy Brown) switch bodies, but not voices — allowing Michael to play his Smallville role as Lex.
- Also, Lex takes advantage of the situation to pull off Flash's cowl and discover his secret identity but is thwarted when he has "no idea who this is." In one Silver Age story, Heat Wave managed to unmask (Barry Allen) Flash and had much the same reaction.
- During the scene here Luthor (in the Flash's body) throws food at Green Lantern, a yellow dessert goes through his shield. In the early comics, the color yellow was used as a deliberate weakness of the Green Lantern Corps as a contingency measure.
- A political pundit cites a book titled The Innocent Seduced as a source proving the link between the Justice League and juvenile delinquency. This references Seduction of the Innocent, the book which made many of the same claims and sparked the creation of The Comics Code Authority. This pundit, by the way, is G. Gordon Godfrey, who, was a full-on agent of Darkseid in Jack Kirby's New Gods series (better known as "Glorious Godfrey").
- Snapper Carr, sidekick/teen mascot of the Justice League in the comics, gets screen time as a reporter.
- In the first episode, when Superman appears dazed, Snapper snaps his fingers in front of his face to try to get his attention.
- The episode "Legends". That's all that needs to be said (although even those savvy to the comics may not have caught the reference to Roy Thomas in the form of "Roy Thompson").
- Also, "The Savage Time". The writers took the opportunity to cram as much WWII comics nostalgia into the three-parter as humanly possible.
- Similarly, in another time-travel episode, John Stewart briefly turned into Hal Jordan as the timeline fluctuated. This is especially notable because Hal never appears in any other context in the franchise, with the Superman series having skipped right over him to feature Kyle Rayner instead, better selling that he's from a radically-different universe created by Chronos mucking around in the timestream.
- There's even a Marvel Mythology Gag in there, as Superman smashes a plane and is covered with burning fuel, briefly resembling the WWII hero the Human Torch (not to be confused with the later model by that name)
- It starts even before the setting shifts to World War II. The alternate-timeline Batman refers to the group of freedom fighters he started in the absence of the Justice League as "orphans and outsiders." In the 1980s, Batman left the Justice League to found a new team called the Outsiders. Naturally, the background characters include cameos by the Robins and Batgirl, and a young Cassandra Cain.
- Likewise, the episode "Ultimatum" features both the Hanna-Barbera Super Friends characters, and a homage to the Keith Giffen-era Justice League of America via the character of Maxwell Lord.
- "A Better World" started out on paper as an episode featuring the Crime Syndicate of America, an evil Alternate Universe version of the Justice League.
- The Royal Flush Gang (first incarnation) are voiced by the actors who voice the main characters in Teen Titans.
- Another Teen Titans reference in "Patriot Act," when Green Arrow calls for backup versus the Shaggy Man...and his ex-sideki— err, ex-partner, Speedy shows up (completing the Seven Soldiers of Victory homage). Same voice actor, look, and general attitude as his Teen Titans counterpart.
- "Patriot Act" also has a Nazi scientist paraphrase the Golden Age descriptions of Superman's abilities when hyping up his Captain Nazi project. The fact this version of said project uses Super Serum rather than genetic alteration can be taken as another nod to Marvel.
- Also in "Patriot Act". The heroes in the parade and the two backups are the present day versions of the Seven Soldiers of Victory, a World War II era team consisting of the Star-Spangled Kid, Stripesy, Green Arrow, Speedy, the Crimson Avenger, the Shining Knight, and Vigilante.
- Vigilante's comment about how he'd have the crowd eating out of his hand if he'd brought his guitar is likely a reference to his comic-book counterpart's career as a country singer.
- In a nod to her invisible plane (from which much hilarity has been mined over the years) from The Golden Age of Comic Books, when Wonder Woman's flying a Javelin, she frequently has it cloaked.
- Linda Park, Flash's wife in the comics continuity, is featured in the Day in the Limelight episode "Flash and Substance" as a fangirl.
- Speaking of "Flash and Substance", the episode also featured the Flash Museum, featuring more Flash Mythology Gag moments than thought humanly possible.
- One more from "Flash and Substance" — Mark Hamill, who regularly plays the Joker in the DCAU shows, plays one of the Flash's foes, the Trickster. Essentially, he's reprising his role from The Flash live-action TV show.
- In "Secret Society", the scene of the League and the Society charging towards each other is a reference to the opening of Challenge of the Superfriends. Earlier, Shade jokingly refers to Grodd's Society as the "Legion of Doom".
- Flash's surreal Dream Sequence in "The Brave and the Bold" when hit by Grodd's Mind Control ray features him growing grotesquely overweight and turning into a puppet — both things featured prominently on ridiculous old Silver Age comic covers.
- Tsukuri and Aresia were based off Katana from the Birds of Prey and The Outsiders, and Fury from Infinity, Inc., respectively. Aresia's debut episode was even called "Fury."
- In "To Another Shore," when Wonder Woman needs to switch from civilian clothes to her costume, she performs the spinning "transformation" sequence from the Lynda Carter TV series, complete with light show.
- The viking corpse who plays the MacGuffin for this episode is himself a callback to an old DC title, Viking Prince.
- In "Eclipsed," Flash suggests to (John Stewart) Green Lantern that they go on a road trip "looking for America," which (Hal Jordan) Green Lantern once did with Green Arrow. He even describes them as "Hard-Traveling Heroes," the name of the story arc.
- In "Maid of Honor," Princess Audrey refers to Wonder Woman as having "feet of clay," to which Wonder Woman responds "You have no idea." Wonder Woman was born when her mother sculpted a baby out of clay, and the gods brought her to life.
- The last scene of the series shows the Justice League running down a flight of stairs in groups; each group has a common bond, such as being part of the infamous "Satellite era" or being Jack Kirby creations.
- The final conversation of the series has Superman jokingly suggesting that Batman must be "going soft" to give the villains a head start, to which Batman replies, "Don't you have a tall building to go leap?", referencing the "able to leap tall buildings in a single bound" line from the classic opening narration.
- "Battle at the Earth's Core" opens with the heroes in Japan fighting a mutated turtle Kaiju. It has a shock of red hair, a sideways reference to Jimmy Olsen, Giant Turtle Boy◊. Commentary on the DVD reveals that they chose not to go that exact route in order to avoid having to explain why the giant turtle turned into a naked Jimmy Olsen when it was defeated, but the turtle itself was left in as an homage.
- And the entire main plot has its setting (and guest characters) taken from DC's old The Warlord title.
- In the comics, Vandal Savage first debuted as an adversary of the original Green Lantern, Alan Scott. John Stewart became the first to combat Savage in "The Savage Time", and the fact that Savage recalls Stewart being the toughest to kill in "Hereafter" is another little nod to his history with Green Lantern.
- In the episode "Paradise Lost: Part 1," Wonder Woman saves a little girl named Cassie and calls her "little sister", a reference to Cassie Sandsmark, the current Wonder Girl.
- Martian Manhunter enjoys Oreos in "Comfort and Joy," which are his Trademark Favorite Food in the comics.
- Most episode titles are based on various DC Comic series, like The Brave and the Bold (whose 28th issue featured the First Appearance of the Justice League) and Weird Western Tales.
- In the two-part "The Once And Future Thing" story:
- In "Part One: Weird Western Tales", Jonah Hex comments on the futuristic nature of the antagonists' gear; when Batman notes this, Hex remarks, "I've had an interesting life", a nod to a brief 1980s retooling of Hex as a time-displaced Mad Max Expy in a Crapsack World future.
- In "Part Two: Time, Warped", members of the League go to the future and meet an older Batman; when the current Batman is warned that things in the future are different he asks his older self, "Are criminals still superstitious and cowardly?"
- In "Starcrossed," Batman wears a diplomat disguise to infiltrate the Thanagarian warship. His disguise greatly resembles Alan Napier, who played Alfred in the Adam West Batman (1966) series.
- Also in "Starcrossed", the name of the Thanagarian villain Hro Talak is an anagram of Katar Hol - the real name of Hawkman, Hawkgirl's Spear Counterpart. A true Hawkman appeared in a much later episode.
- In "A Better World," Batman's password, 91939, is the combination of two historic dates: the year of his first appearance in Detective Comics in May, 1939, and Adam West's birthday, September 19, 1928.
- In "Secret Society," Grodd's society (Himself/Sinestro/Shade/Giganta/Clayface/Killer Frost) charging toward the League in a balls-out glorious homage to the old Challenge of the Superfriends intro.
- In "Task Force X," Plastique is tended to by Captain Atom after she is injured and left behind by the rest of the team. In the comics, the two end up getting married.
- In "Injustice For All," in the final fight between Lex's group and the League, a statue of Zan and Jayna is smashed.
- In "Comfort and Joy," the cat that lives in the Kents' house is pretty clearly Streaky the Super-Cat. It has no powers, however.
- In "Patriot Act", General Eiling's giant mutated form is identical to the Shaggy Man body he transfers his mind into in the comics, although the character, method and storyline are completely different. In fact, how he goes about here is tied to Shazam! villain Captain Nazi. The group of heroes at the parade in that episode were an amalgamated lineup of the Seven Soldiers of Victory.
- Tom Turbine in "Legends" explains a vibration-based multiverse theory which is pretty close to how the pre-Crisis DC multiverse worked.
- When Brainthor creates robot Justice Lords to distract the League, he's forced to create a new one for Flash (since Flash's death was what created the Justice Lords in the first place). The being he creates is nearly identical to Professor Zoom AKA The Reverse Flash.
- "Ancient History" tells the story of Hawkman and Hawkgirl's original selves in Ancient Egypt. It is said that Teth Adam paid tribute to them. Teth Adam is the man who would become Black Adam in DC's mainstream continuity.
- In "Alive," Cheetah and Bizarro are the ones to hook up Lex's machine in space, likely a callback to "Wanted: The Superfriends", where the Legion rewired the JL satellite to make the world into slave clones of the two.
- Also from "Eclipsed": one of the possessed characters (as per another's sarcastic suggestion), in order to attract the JL, "puts on a gaudy costume and threatens to hurt a lot of people". He ends up looking exactly like the original comic book version of Eclipso (who has a very different origin and background).
- In the Project Cadmus arc of Unlimited, Supergirl's evil clone Galatea looks and dresses exactly like Power Girl, who's Supergirl's Alternate Universe doppelgänger in the comics.
- "Flash and Substance" references that Wally West is the third Flash in the comics, though he otherwise appears to be the only Flash in the series and the references themselves are never explained further. The Flash Museum has the helmet of the first Flash, Jay Garrick, on display. At work in a police lab, Wally mentions an unnamed uncle is "flying in" to see him. His uncle is Barry Allen, the second Flash, who had the same job. Furthermore, Wally's saying this to a blond guy who looks just like Barry Allen.
- "Maid of Honor" has Princess Audrey promising that she won't tell anybody that Wonder Woman has "feet of clay." Wonder Woman replies, "You have no idea." Wonder Woman was forged from clay by her mother.
- Another "Comfort and Joy" one: someone◊ walking behind Green Lantern and Hawkgirl looks a lot like Swamp Thing.
- In "Question Authority", the soda that Superman and Lois drink on their date is Soder Cola - the brand that Booster Gold frequently hawks in the comics.
- The episode also features several nods to Question's Watchmen counterpart Rorschach - Q's apartment has an opened can of beans sitting on one of the tables, and at the end of the episode, his facial injuries are similar to those suffered by Rorschach during his arrest.
- In "Hereafter", Batman's private eulogy to Superman (who is presumed dead, though Bats has been trying without success to prove that he isn't) is interrupted by a distant explosion caused by supervillain celebration of Supes' demise. Batman addresses Superman's memorial, "What did you always call it, Clark? 'The Never-Ending Battle'?"
- Another from "Starcrossed": during the fight in the Batcave, one of the Thanagarians smashes into a display case that has Mr. Freeze's gun in it and, in desperation, grabs the gun and fires it. Unfortunately for him, Superman isn't weak to ice like Inque is.
- In the pilot, J. Allen Carter, the man who unwittingly frees the invaders from Mars, is almost certainly a reference to John Carter of Mars. His partner, Ed Reiss, is likely a play on Edgar Rice Burroughs.
- The next episode, "In Blackest Night" features a very brief cameo from a Burroughs-style Green Martian, trapped in one of the cells on Ajuris-5.
- In the 2-part story in "Panic in the Sky" and "Divided We Fall", Brainiac residing within Luthor's body and then becoming a Body Horror hybrid of them both is from the comics story Whatever Happened to the Man of Tomorrow?. The episodes invert the original story in that Luthor accepts what happened to him and then convinces Brainiac that they work together as equals to both their greater mutual purposes.
- In Issue #38 of the Comic-Book Adaptation, the Flash sits next to a billboard for Rosenbaum and Associates. The comic is based on a cartoon where the Flash is voiced by Michael Rosenbaum; and the guy posing for the billboard is bald like Lex Luthor, who used to be portrayed by Rosenbaum in Smallville.
- In an issue of the tie-in comic, Flash goes on a date with a girl named Jesse, likely Jesse Chambers (also known as fellow speedster Jesse Quick in other continuities).
- In "Far From Home", Emerald Empress mentions that the Green Lanterns are now a rare sight in the 30th century. In the pre-Zero Hour: Crisis in Time! comics, the Green Lantern Corps were banned from Earth by the Guardians after Universo tried to use his power ring to see the Dawn of Time to become a god. Universo also got his ring confiscated and he ended up becoming a villain to the Legion of Super-Heroes.
- In "The Greatest Story Never Told", the overall villain is Mordru, typically seen as a Legion of Super-Heroes villain in the far future, and his attack is causing weird chaotic events, evidenced by the brief joke when Batman and Superman are merged into a composite being (like in the Silver Age World's Finest stories) who speaks with Wonder Woman's voice. Booster Gold ends up saving them all from an ancillary threat indirectly caused and made worse by Mordru's attack. The story is told from Booster's POV, which makes it all seem even more frenzied and chaotic, since he is deliberately kept on the fringes. This kind of wild/goofy-at-times scenario roughly resembles Mordru's last non-comics association with the Justice League, the infamously awful Legends of the Superheroes live-action specials.
- The robots that the League trains against in "Secret Society" are the Z-8 model originally introduced with Zeta in Batman Beyond, making this a Call-Forward as well. Another one is sicced on Supergirl in "Fearful Symmetry".
