Owlman didn't turn off the bomb because, in another universe, he chose to turn it off.It's the The Multiverse rule.
The Anti-Monitor caused the reversal of roles in this new universe.
Owlman was wrong about his theory of the multiverse.Otherwise, there would have been an infinite number of universes in which he succeeded in destroying the multiverse, which is impossible because there are not an infinite number of multiverses.
The QED was an Owlman Gambit that failed.He's the equivalent of Batman, and so must have the equivalent of Batman Gambits. And why would he want to wipe everyone out?
Earth Prime really is Earth Prime.Superboy-Prime lives there, after all, and we all know how irritable he can be. Taking into account his most recent misadventure, it doesn't take a whole lot of imagination to guess what happened. Nekron was defeated and BL-Laurie was destroyed before she could kill him. In a rage, he laid waste to the Earth and set out to do the same to a defenseless universe.
Rose Wilson's mother was anti-Syndicate.The real reason why she was assassinated. All the more reason why Rose decided its time to stand up against them. The reason why Slade tries to talk her out of it because she doesn't want her to end up dead like her mother. Rose blames her father for her death, in a way, because he had the power to stop them but chose to bow down to their demands.
Johnny Quick's other "counterpart" is Owen MercerIn comics canon, Owen is the long-lost son of the blindingly Australian George Harkness/Captain Boomerang, and apparently inherited superspeed from his mother's side of the family. Superficially, he's a redhead like Johnny (and Wally). Maybe on this Earth, instead of being adopted by the American Mercers, Owen was raised by his father's family in Australia. Instead of ending his life feeding children to zombies, he helps save the multiverse through Redemption Equals Death. This might mean his legal name is John Harkness.
On one of the other Earths, Owlman is Adrian Veidt
Had the film still been "officially" part of DCAU by the time it was completed, a Justice Lords reference would've been inevitable.Basically a "we've encountered alternate versions of ourselves before, but they weren't exactly evil but rather too extreme" line somewhere in there.
There is Star Trek in this universe but it all takes place in the Mirror Universe seen in Mirror Mirror
President Slade Wilson was a member of Parallel!Luthor's Justice LeagueHe was the heroic version of Deathstroke, but he had a Secret Identity, of coarse. Lex did seem to speak to the President like he was an old friend. He left and hung up the costume because of some injury that prevented him from continuing, which is why he didn't use that identity during the film. He ran for president so he could help out from the sidelines, but when the Crime Syndicate started killing heroes and threatening innocents, he decided he needed to obey to spare as many lives as he could.
This movie is in the same continuity as Batman: Under the Red HoodBoth films have a slightly older-sounding Batman than normal.
The parallel Earth in this film is the only one in the multiverse where the Crime Syndicate lasted long enough for outside intervention to be necessary to defeat them.I know this doesn't quite match how Owlman says the multiverse works, but it would definitely explain why we don't see dozens of Batmen and Owlmen on Earth Prime. Plus, it would (ironically) add extra meaning to the way the movie ends.