- Awesome, Dear Boy: George Pérez actually made himself contractually obligated to draw this crossover when it was Saved from Development Hell for this reason.
- Development Gag:
- Captain America and Batman's fight was originally planned to go to completion. Cap would've won, after a while. In the actual book, they spar for a few moments before calling it off, with Batman admitting that Cap could win, after a long time.
- When the Marvel and DC universes are given a merged history, The Wasp recalls the original proposed storyline (the '80s-era teams battling Kang and the Lord of Time) as a previous meeting of the two teams.
- Doing It for the Art
- The cover for the third issue, representing every member either team had in its 40+ years of history. 208 characters in total. Perez actually injured his wrist drawing that cover, which delayed the miniseries for about a month.
- There's a page where a bunch of DC characters are stacked up against their Marvel characters on various chessboards. If you squint real hard, you can see Death of the Endless face to face with Marvel's Death.
- Unfinished Episode: A Justice League/Avengers crossover was created 20 years before JLA Avengers came out. The script was completed and George Pérez started illustrating it but then Marvel and DC had a falling out. By the time they reconciled enough to try again the cast lineups and universe history changes necessitated scrapping the original script and starting from scratch.
- Although, it also had an insanely awesome plot point in it: Hawkeye and Green Arrow hit an object at the dawn of time, causing the big bang.
- What Could Have Been
- As noted under Development Gag, Kurt Busiek's original plan was for the Batman/Captain America fight to play out all the way, with Cap eventually winning.
- The original plan for chapter three of the story was that the Justice League would have an adventure with Marvel-style storytelling and the Avengers would have an adventure with DC-style storytelling. Perez would even draw the Avengers in the style of Carmine Infantino and the JLA in the style of Jack Kirby. Ultimately it was decided that this would slow the story down too much and it was discarded. The original plan was:
- Captain America - Senator Steve Rogers lives in Capitol City. From his secret base of operations underneath the Lincoln Memorial, he fights crime, aided by his assistant Jasper Sitwell. Steve's former sidekick James "Bucky" Barnes now leads his own team, the Young Allies, while his ex-girlfriend Sharon Carter has become a hero of her own, the Golden Girl.
- Iron Man - Dr. Tony Stark lives in an orbital community known as "Transistor Station". Assisted by three teenage interns — Pepper, Happy and Rhodey — Tony remotely controls a variety of advanced robotic suits of armor from the Telepresence Unit in his office in battle against the forces of evil.
- Thor: Everyman Donald Blake is bestowed the power of Thor after the god of thunder is slain in Ragnarok and must wield the mighty Mjolnir to protect the cosmos from Asgard's enemies.
- Hawkeye - Clint Barton is the hotshot star of "Hawkeye, Bullseye Detective", a TV show in which he goes around the world solving crimes in his arrow-shaped flying motorcycle. His devil-may-care attitude drives producer Bobbi Morse insane, but it's clear they care more about each other than they let on.
- Quicksilver and Scarlet Witch - Peter and Wendy Maxwell are teenage siblings from Hex Valley who have been bestowed items of great power by benevolent aliens that they useto fight crime: Peter has boots that grant him superspeed and Wanda was a tiara that allows her to warp reality.
- Batman - Blind teenager Bruce Wayne lives in New York City with his stepfather, Alfred Pennyworth after his parents' death in an accident which also afforded him a bat-like sonar, which he uses to fight crime. Alfred's employer, Commissioner James Gordon, believes Batman to be a menace and is determined to arrest him. He sponsors Bruce's admission into a prestigious boarding school, where Bruce falls in love with Gordon's daughter, Barbara, but can't pursue her due to Gordon's disapproval.
- Superman - Extraterrestrial scientist Dr. Calvin "Cal" Ellsworth accidentally destroyed his homeworld Krypton in one of his experiments and is determined to free his people from the Phantom Zone, as well as prevent them from trying to enslave humanity.
- Wonder Woman - The Olympian Goddess of Hunt, who abandoned Mount Olympus to live among them as a hero.
- The Flash - Disgraced baseball player Barry Allen ingests an unstable performance-enhancing serum that causes him to transform into an irrational creature of pure speed whenever he becomes agitated, and struggles to channel his curse to do good.
- Green Lantern - Military pilot Hal Jordan operates a suit of armor made from the wreckage of a spaceship and powered by cosmic energy to defend the world.
- Martian Manhunter - J'onn J'onzz, the shapeshifting spearhead for a Martian invasion, grows fond of humans and betrays his masters to defend mankind.
- Hawkman - Joe Carter is a paraplegic NYPD detective whose partner and lover, Thalia Says, was killed in the same accident that crippled him. Carter finds the Sword of Khufu, an ancient magical artifact that hosts the Hawkman, an avenging spirit from the Egyptian lore. By summoning the sword's power, Carter becomes a vessel through which the Hawkman returns to life to dispense justice on the criminals and the corrupt.
Trivia / JLA/Avengers