UPDATED with Atom appearance.
The following is every easter egg, in-joke, hidden message and callback we spotted in Justice League. We’ll add to the list as and when we spot more. And obviously, BEWARE OF SPOILERS AHEAD.
The Atom Appears in Justice League, Kind Of
An eagle-eyed Redditor has spotted mention of The Atom early in Justice League. When Silas Stone is busy trying to bring son Victor back to life, a S.T.A.R. Labs computer screen can be glimpsed. And on that screen there is a list of names, one of which is Ryan Choi. A scientist and physics professor, Ryan Choi was the fourth Atom to appear in the comics, debuting in Brave New World #1. No word yet as to whether Atom will ever actually join the Justice League onscreen, but it’s a nice little nod to fans of the character.
Boom Tube
The ‘Boom Tube’ is the teleportation device that allows Steppenwolf and his Parademons to travel from place-to-place in the movie, and through dimensions and wormholes in space.
Janus
Early in Justice League you can glimpse a building with ‘Janus’ emblazoned on the side. Janus Cosmetics was a make-up company owned by the villainous Roman Sionis. Lucius Fox purchased the company on behalf of the Wayne Foundation on the proviso that Roman step down as President. Which angered Roman so much that he became super-villain Black Mask.
Janus also harks back to The Janus Directive, a 1989 comic book storyline that pitted government agencies Task Force X, Suicide Squad, Checkmate, Force of July, Project Atom and Project Peacemaker against each other while Kobra endeavoured to take over the world. The Janus Directive was a false piece of intelligence sent to each agency.
The New Gods
Steppenwolf criticises the Old Gods during Justice League, and states that he is uniting the Mother Boxes so he can take his place among the New Gods. The New Gods are beings who live outside of time and space in a realm called the Fourth World. In the comics, Steppenwolf is a member, as is Darkseid, while a full list of New Gods can be found here.
The Music
During key scenes in the movie, the score harks back to John Williams’ 1978 Superman music, and Danny Elfman’s 1989 Batman tune. A grim reminder of when superhero scores were good.
Penguins
Batman Returns callback courtesy of Alfred: “One misses the days when one’s biggest concerns were exploding wind-up penguins.”
Evil Superman
When he’s brought back to life, a confused Superman turns on the Justice League. And he has form on that front. There have been multiple ‘bizarro’ Supermans in the comics. On film, he turned bad in memorable fashion during Superman III, punching a hole in an oil tanker, getting jiggy with the lady-villain, fighting Clark Kent, and even flicking peanuts at a mirror.
Wonder Woman Epilogue
A Wonder Woman scene that was shot for the DVD features Etta Candy telling Steve Trevor’s crew about the discovery of something that’s “very old and very powerful.” That would be the third ‘Mother Box‘ which we’re told the Brits found during WWI.
Green Lanterns
As Wonder Woman fills Batman in on the Mother Boxes, and the war that was fought thousands of years ago against Steppenwolf when he first tried to take over Earth, a flashback sequence shows us scenes from an ancient battle.
She tells how Amazons, Atlanteans and all the tribes of man fought together with gods and powers from other worlds to drive Steppenwolf away – and it’s at this point we see Green Lanterns involved in the skirmish. The sequence closes with one of their number dying and we see his power ring fly off his finger skywards.
Ares and Zeus
In that same flashback battle, Ares — the big and none-too-memorable bad from Wonder Woman — and Zeus do battle with Steppenwolf. Zeus is the dude throwing round lightning. Obvs.
Pet Sematary
When Superman comes back to life, The Flash references Pet Sematary multiple times. Pet Sematary is a Stephen King novel from 1983, about pets and kids returning from the afterlife, with dire consequences. It was turned into a movie in 1989, directed by Mary Lambert, and starring Dale Midkiff, Fred Gwynne and Denise Crosby.
Booyah!
Cyborg’s catchphrase in the Teen Titans animated show is “Booyah!” Victor Stone says just that near the end of Justice League. In somewhat clumsy fashion.
Deathstroke
The second post-credit sting sees Lex Luthor summoning Deathstroke and revealing his plan to form a villainous league. The scene sets the character up for his role in forthcoming standalone movie The Batman, while it’s clear that the bad guys will be teaming up for Justice League 2.