BEWARE OF SPOILERS!
DC Extended Universe
- At the end of Batman v Superman: Dawn of Justice, Wonder Woman states that she abandoned the world of men one hundred years ago, with the clear implication that she gave up on humanity after her experiences in the First World War. However, when we actually see those events in her own film she comes close to the Despair Event Horizon after Steve Trevor's death, but doesn't cross it, rejects Ares' Humans Are Bastards worldview, and is not shown abandoning humanity at the end. Justice League (2017) reinforces this further as, while it doesn't get specific, it does state that Wonder Woman came to humanity's defense many times in between 1918 and the events of Dawn of Justice. Made explicit with Wonder Woman 1984, where Wonder Woman is an active superhero during The '80s, though to maintain continuity she takes some efforts to conceal her involvement in heroic activity.
- For a "softer" retcon, we have Superman's personality and relationship to the world. Man of Steel and Batman v Superman: Dawn of Justice gave him an Adaptational Angst Upgrade and made Beware the Superman a major plot point, while Justice League basically drops these tropes and tries to convince the audience that no, he was always this friendly and everybody loved him, really.
- Aquaman drastically altered many aspects of Arthur Curry's personality and backstory established in previous films. Most notably, Arthur went from blaming his mother Queen Atlanna for her parental abandonment in Justice League to blaming Atlantis for arresting and apparently executing her for marrying his human father Thomas. Also, Mera's hair is bright red instead of the more common redhead color she has in both versions of Justice League.
- The theatrical cut of Justice League also tried to explain Aquaman's ablity to commune with sea life as mystical and abstract. In Aquaman it's shown that he can literally talk to sea life. The Snyder Cut never acknowledged this ability outside of Arthur's establishing scene, keeping the issue vague enough to avoid continuity problems.
- While Wonder Woman 1984 doesn't outright contradict Justice League (either version), it does create the impression Diana is leaving out some significant context regarding her past with Steve — specifically, the fact that she's lost him not once, but twice.
- Zack Snyder's Justice League: While the basic story remains roughly the same between this version and 2017's Justice League, several elements have been changed (or more exactly, reverted back to what was originally intended by Zack Snyder and Chris Terrio) in this version.
- About the "Mother Box Origins" trailer
, Zack Snyder confirmed that Diana/Wonder Woman first saw action during The Crimean War and not World War I unlike her solo film debut (the helmets at her feet) and that Arthur/Aquaman's father is dead by the time of the film (there's a funeral urn by his side) while he's very much alive (played by Temuera Morrison) in his solo film that's supposed to take place after Justice League. - Darkseid is very much involved in the story instead of just getting named. He led the invasion of Earth in the past and killed a Green Lantern, where it was Steppenwolf who did this in the 2017 film.
- Steppenwolf's design has changed and he wears a collapsible, dynamically morphing armor. His personality and motivations are also different, being more clearly driven to prove himself to Darkseid and being more of a No-Nonsense Nemesis instead of a bombastic and sadistic jerkass.
- Steppenwolf makes use of a Mind Probe device to find the Mother Boxes, whereas in the 2017 film he only uses Jack Bauer Interrogation Technique.
- Lois Lane still works at the Daily Planet in the 2017 theatrical version, while here she hasn't come back at her job for a few months out of grief. For that matter, she doesn't meet Martha Kent but the Martian Manhunter in disguise instead.
- The stronghold in which the Amazons kept their Mother Box isn't just sealed, it also collapses into the ocean, killing the Amazons who were trapped inside.
- A point that retcons something from Aquaman: Atlanteans don't speak underwater unlike what they do the latter film (Snyder was adamant about speaking underwater not being "realistic"). They communicate using dolphin-like sounds, unlike the theatrical version in which they don't communicate at all, they're only able to talk in air bubbles. The film also gives Vulko the same air bubble power as Mera, which he didn't seem to have in Aquaman.
- Speaking of Aquaman, the sailor he saves and drops on a bar table has had no encounter with the Parademons this time around.
- Alfred doesn't mention "wind-up penguins", leaving it more ambiguous if Bruce/Batman ever crossed path with The Penguin.
- The dynamic between Victor and Silas Stone plays out differently. Silas is more estranged and his son himself accuses him of having "created a monster". And Silas dies instead of having a Happy Ending.
- Victor is more serious overall as well, with no quips nor a certain catchphrase being used this time around.
- Barry Allen/Flash doesn't save people by moving them around at Super-Speed in the tunnels battle. Instead, he uses his speed to prevent debris from falling on them (moving people around at his speed would be fatal to them). The only person he moves around to safety is Iris West, and he takes extreme care when doing so, no moving her across a long distance either.
- The League doesn't have a conflict over reviving Superman (but Aquaman does express grave reservations about it and doubts that it's really Superman at first), and Bruce isn't an Adaptational Jerkass anymore (what with reminding Diana of Steve Trevor for mockery in the theatrical version).
- The fight against a revived Superman sees Batman making use of deflecting gauntlets that Alfred built to absorb Superman's Eye Beams. In the 2017 version, Superman grabbed him by the chin and threw a line from Batman v Superman: Dawn of Justice ("Do you bleed?!") back at him.
- Superman wears a black suit instead of a blue one (it was digitally darkened).
- There's no alarm on the Batmobile to lure the Parademons.
- Nothing indicates that Parademons are attracted by fear, they simply follow the scent of the Mother Boxes. They also don't turn into action bombs.
- The Russian town of Pozharnov is abandoned instead of having people who live there (such as the family in the 2017 film).
- The Unity of the Mother Boxes produces an explosion that disintegrates everything in its path instead of terraforming with large crystal tentacles.
- The Final Battle plays out differently: Batman stays outside the fortress to destroy Parademon defenses and keep them at bay (instead of fighting inside and running out of blaster ammo), Cyborg needs the energy that Flash produces when running to get inside the Unity instead of simply interacting with it, neither Flash nor Superman need to save townsfolk since the town is abandoned, Steppenwolf's axe is destroyed by Superman himself instead of Wonder Woman (and Superman only needs a small puff to freeze it instead of a sustained blow), and the unity kills every Justice League member except Flash (temporarily intangible) which prompts him to run as fast as he can to Time Travel and prevent this from happening. Also, Steppenwolf doesn't tear off Cyborg's leg.
- Steppenwolf gets impaled by Aquaman's quindent, Punched Across the Room by Superman and beheaded by Wonder Woman, and his corpse lands on Apokolips at Darkseid's feet via a Boom Tube instead of being beamed back alive to Apokolips. Basically, team work is used to bring him down instead of just Superman's intervention.
- At the end, Batman stands on a tank-like vehicle straight out of Batman: The Dark Knight Returns instead of facing his Batwing.
- The Justice League doesn't count six members at the end but seven instead, with the addition of Martian Manhunter.
- About the "Mother Box Origins" trailer
