Just as Ben is starting to feel bored of working with others, a being known as Alien X appears to steal the Omnitrix, resulting in him having to call in some help.
This episode contains examples of:
- Alliance of Alternates: Ben eventually defeats Alien X by working with 4 different versions of himself (plus a version of Gwen).
- Alternate Universe: The focus of the special is on this.
- Alternate Universe Reed Richards Is Awesome: Future Max has a cybernetic arm, a Rustbucket pimped out for Omniversal travel and technology to undo Celestialsapien reality warping and the Omnitrix's coupling.
- Back for the Finale: As the last episode of the reboot series, that crosses over with the 4 original series, the returns of Chromastone, Big Chill, Ampfibian, Bloxx and Ripjaws count as this.
- Brick Joke: Throughout the Action Prologue, Ben and Gwen mock Zombozo for buying what they assume to be cheap party supplies. After he gets arrested and handcuffed, Zombozo admits that maybe it was cheap, given how secure the handcuffs are.
- Call-Forward: UA!Ben tells AF!Ben that he'll get the Ultimatrix if he plays his cards right.
- Clown Car: Discussed. Zombozo claims that they’re not as spacious as you'd think. ("Plus my roommate Randy keeps his junk in there.")
- Crippling Overspecialization: All of the alt!Bens stick to one alien each (Original!Ben with Heatblast, UA!Ben with Ampfibian, Omniverse!Ben with Bloxx and Gwen 10 with Ripjaws), except for AF!Ben, who gets two (Chromastone and Big Chill).
- Despair Event Horizon: Alien X is a version of Ben who went through this after Vilgax killed his Gwen and Max, becoming convinced that he should be the only one with any power.
- Dramatic Irony: Upon learning that her alternate self has a crush on Kevin, Gwen is perturbed. While this would be a normal reaction concerning their Kevin, they have no idea that version of Kevin is past his evil ways (mostly).
- Era-Specific Personality: The 4 Alternate Bens have this, with Original!Ben being mostly identical to Reboot!Ben, AF!Ben being more mature and responsible, UA!Ben being more egotistical and Omniverse!Ben being the least mature of his teenage incarnations.
- Foreshadowing: While Ben is trying to stall Alien X while the Omnitrix recharges, Alien X remarks that he remembers joking. That's because he's another version of Ben.
- I Have Many Names: AF!Ben notes that the Plumbers in his dimension don't call the seemingly rogue Celestialsapien "Alien X" (likely to avoid confusion with Ben's transformation of the same name).
- Implausible Deniability: Grandpa Max is very eager to deny the existence of the Plumbers once AF!Ben gives his explanation of them, despite the very obvious "ix-nay" motions he was making throughout.
- Jerk with a Heart of Gold: Future!Max acts like a dick to Reboot!Ben throughout, but it's because he's seen Alien X injure or kill multiple Bens (including his own) and wants to stop that from happening.
- Musical Nod: The appearances of AF and UA!Bens are accompanied by the theme tunes for their series. Similarly, Original!Ben gets an instrumental of his theme when he transforms into Heatblast.
- Mythology Gag: Future!Max resembles, as the name implies, Max's look in the original series's first look at the future.
- Replacement Goldfish: Future!Max decides to leave on an omniversal road-trip with Evil!Ben after his defeat, replacing the grandson the former lost and the family the latter lost.
- Title Drop: Original!Ben declares "Prepare for Alien X-Tinction" before transforming.
