Adaptational Badass: Alt-Beast whom is supporting some sort of Powered Armor. Also alt-Magneto whom was able to completely destroy robots with only using magnetic energy while his mainstream counterparts was nearly killed while fighting against Sentinels.
Adaptational Heroism: Sinister and even Holocaust are seen as members of the Mutant Resistance in the alternate reality.
Adaptational Villainy: The Avengers from the other timeline oppose the X-Men and fight in the side of the humans. Adverted with Beast, who is working for La Résistance instead of Apocalypse and his cult.
Adapted Out: Even though the alternate timeline is based on the Age of Apocalypse, Apocalypse doesn't appear and the war is between mutants and humans instead of Apocalypse and his mutant supremacist followers against humans and the rest of mutants.
Alternate Reality Episode: Most of the episode takes place in the altered timeline in which Xavier was murdered before he became an activist for peaceful mutant-human coexistance.
The Cameo: Many members of the Mutant Resistance: Blink, Mimic, Sabretooth, Wild Child, Angel, Colossus, Nigthcrawler, Sinister, Holocaust, Gambit, Tar Baby, Copycat, Frenzy, Rogue, Morph, Jean Grey, Blob, Caliban, Callisto, Pyro, Masque, Mastermind, Sunder, Sunfire, Polaris, Banshee for the Resistance.
And on the side of the "Avengers": Captain America, Giant Man, Iron Man, Black Widow, Wonder Man, Wasp, Daredevil and Scarlet Spider.
Continuity Nod: While explaining to the alt-Storm and alt-Wolverine the timeline, they show holograms of their timeline which also includes footage from Days ofFuture Past
Downer Ending: The episode ends with Bishop, Shard, Logan and Storm failing to save Xavier.
The Medic: Dr. Summers (clearly Cyclops) for the Resistance, with Jean as a battlefield nurse.
The Quisling: Trevor Fitzroy collaborates with Master Mold hoping to become the most powerful mutant in existance.
Refusal of the Call: Young Xavier is overwhelmed by the notion he'll lead the X-Men and work towards mutant-human coexistance. Logan is also reluctant to aid in a mission that will result in his and Storm's Ret Gone.
World of Badass: Pretty much describes everyone in the alternate timeline, considering they're fighting a Hopeless War in midst a ruined world. For instance Beast, whom is a lot more willing to fight than his mainstream counterpart.