- Hey guys! If you're just joining in, we're in the middle of a story arc.
SMG3 has finally revealed his master plan to erase SMG4 and the Gang; have himself and the Anti-cast travel back in time to the episodes the gang first debuted in and alter the past, erasing them from the present. Now the SMG4 gang must stop them before its too late.
- Beware the Silly Ones: The Anti-cast (save for JubJub and Whimpu) succeeds in keeping Mario for meeting the main cast, with Belle's gaming skill winning against Tari, Rob becoming a massive corn monster to scare off the bros., the Weegee Doll replaces baby Luigi with himself, and even Melony knocks out Mario long enough for him to missing the Squid Sisters’ broadcast. SMG3, who was a mostly a harmless baddie, manipulates Mario yet again into kicking out SMG4 by telling him he's a personal gym teacher, erasing every single one of them.
- Continuity Cavalcade: The entire episode is a massive call back to the debut episodes of the main gang. During SMG4's debut episode, it even goes back to the old style he used then.
- Downer Ending: SMG3 succeeds in erasing SMG4 and the rest of the main cast besides Mario (and possibly Peach, Bowser, and Axol) via Ret-Gone. Cue silent credits.
- Face Death with Dignity: Unlike the others, who react to getting erased with varying degrees of fear and despair, Saiko just gives an annoyed Aside Glance before turning to dust.
- For Want Of A Nail: SMG3's plan to erase the Glitchy Gang is to have his Anti-cast travel to the their debut episodes and cause these, which will cause their present self to vanish.
- Frankie is replaced by Tinky Winky wearing a Toad cap.
- Belle convinces Mario to have her as his gaming trainer by beating future Tari in a game match.
- Rob blocks the sewer Mario and Luigi were trying to go throw with corn, and scares them off by becoming a corn monster, preventing them from ever meeting Bob.
- Whimpu stops Boopkins from bring Saiko to life by showing him other games, and Saiko accidentally seals her own fate by breaking the laptop she was spawned from while trying to get rid of him.
- JubJub fails to do anything, but Boopkins crashes into his younger self and they both get sent into a black hole, making the whole thing moot.
- The Weegee Doll replaces baby Luigi with himself and convinces baby Mario that it was his brother.
- Melony conks Mario unconscious while he was watching the Squid Sisters’ announcement, preventing him from learning of Splatfest and going after Meggy.
- SMG3 convinces Mario that SMG4's a personal gym teacher, kicking him out of the castle.
- Given Name Reveal: The Superpowered Evil Side of Shroomy has here been given the name Anti-Shroomy.
- Hypocrite: The Weegee Doll is the most shocked at what SMG3's plan does to its victims, considering Frankie was just a kid. In Luigi's "debut episode," he flings off the baby Luigi and convinces baby Mario he's his brother.
- I Lied: SMG3 admits that his burying of the hatchet back in I Can't Believe That It's Not SMG4! was a ploy to keep SMG4 off his back while he finalized his master plan.
- Meet Your Early-Installment Weirdness: When SMG4 went into his debut episode, he comments about how his old videos used to look like that.
- Never the Selves Shall Meet: SMG4 warns the others not to meet their past selves, otherwise they'll "open a black hole and die". Sure enough, Fishy Boopkins interacts with his past self, and both of them end up getting sucked through a wormhole.
- Nice Job Breaking It, Hero:
- Saiko accidentally seals her own fate by breaking the laptop she was spawned from while trying to get rid of Whimpu.
- JubJub fails to do anything to keep Mario and SMG4 from meeting his brother, but Boopkins himself crash lands on top of his younger self and both get sucked into a black hole.
- Mario, twice due to the Anti-cast; the first due to him getting knocked out by Melony and missing the Splatfest broadcast, and he instead decides to get food and ends up erasing Meggy, and thanks to SMG3, he kicks SMG4 out of the castle due to thinking he's a personal gym teacher.
- Red Eyes, Take Warning: Bob's eyes are angrily glowing red when with the rest of the gang confronting SMG3.
- Screw This, I'm Out of Here!: Rob scares off Mario and Luigi by becoming a huge corn monster, preventing them from meeting Bob.
- Switched at Birth: How the Weegee Doll gets rid of Luigi. Traveling to the day and hospital the bros. were born in and replacing Luigi's baby self with himself and convincing baby Mario it was his brother.
- Wham Episode: The (almost) whole cast gets replaced by copycats of themselves.
- Whole-Plot Reference: The story (wherein the core cast goes back in time to critical moments in their history to Set Right What Once Went Wrong) is one to Avengers: Endgame, though the outcome (all of them fail, leading to them fading to dust) is clearly inspired by the ending of Avengers: Infinity War.
- Would Hurt a Child: Twice.
- To demonstrate how his plan works, he has Tinky Winky travel back to the episode where Frankie was first introduced in and replace him, causing Frankie to disappear in the present.
- To get rid of Luigi, the Weegee Doll hurls Luigi's baby self out of the crib he was in with baby Mario in order to replace him.
