Batman's armor is the prototype for the Batman Beyond suit
A red and black full-body armor with retractable wings? Come on.Supergirl was in Gotham when the Legion of Doom ambushed her...
... because she wanted to check on Batgirl and ask her help to find her cousin. Since this universe is based on Earth-One, Kara and Barbara are still friends here.Pa and Ma Kent are dead in this universe
Superman was said everyone he cared about were kidnapped. We see Lois, Jimmy and Supergirl... but Pa and Ma were not seen.Alternate explanation: They were off-panel.
Another alternate explanation: Pa and Ma were not kidnapped because the villains are fightened of Martha Kent.
Justice takes place in a universe similar to the one at the end of Crisis on Infinite Earths.
The comic could take place in a Hypertimeline that was branched from the real Post-Crisis universe, somewhere between CoiE #11 and All-Star Squadron #60 before the changes settled in.- Kara Zor-El still exists. But she'll still meet her demise.
- The Marvel Family made their debut during the "new age of heroes".
- Hawkman and Hawkgirl are the Thanagarians Katar and Shayera Hol.
- Wonder Woman is a founding member of the Justice League (which post-Infinite Crisis made canon again).
- Villains like Metallo, Toyman, Giganta, and Black Adam made their early debuts than later like in Post-Crisis. Although Superman: Secret Origin had Metallo appear during Superman's early years. And Giganta started out as a gorilla instead of a human woman.
- The Maxwell Jensen Parasite still exists.
- Bizarro appears to be an "imperfect duplicate" instead of a failed clone of Superman.
- Priscilla Rich is a contemporary like in the Silver Age instead of being a Golden Age villain like in Post-Crisis.
- Flash's parents are still Happily Married, his mom wasn't murdered by Reverse-Flash and his dad wasn't sent to jail.
The Legion of Doom members only start wanting to take over the world rather than actually save it after being mind-controlled.
- There are a few moments in earlier issues which suggest that at least some of them may really care about the world as more than just something to rule over, such as when Cold talks about hoping his actions will stop the apocalyptic nightmares he has and Manta says that Aquaman deserves a brutal death for causing the visions he saw, both of which might have Undercover When Alone implications otherwise.
John doesn't really erase everyone's memories of the heroes' identities at the end but only thinks he did.
Heroes like Elongated Man were targeted but left alone due to the brainwashed villains assigned to abduct them Fighting from the Inside.
Hal's nieces and nephews, Damian Wayne, Dolphin, Diane Meade, Uncle Dudley, Lana Lang, Sapphire Stagg, Tim Drake, Jason Todd, Catwoman, Harold Allnut, Stephanie Brown, Giovanni Zatara, Silver St. Cloud, Captain Frye, Patty Spivot, Tina McGee, and various other friends and loved ones of Justice League members were also kidnapped but are offscreen in the background or were targeted but escaped.
The disease-curing, limb-replacing, and hunger-solving works Brainiac has Scarecrow, Toyman, and the Riddler introduce to Earth as part of his Evil Plan stick around, are cleansed of their corruptive attributes and contribute to the Utopian future in the Legion of Superheroes time, giving those villains a Nice Job Fixing It, Villain legacy.
