The time-travel mission to stop Robotnik has failed; his armies have already taken Mobotropolis! Also, Sonic and Sally have somehow put their younger selves and the Knothole Village in the Great Forest at risk.
This episode provides examples of:
- Bittersweet Ending: Sonic and Sally failed to stop Robotnik's takeover in the past, but they still created a new timeline where their nanny Rosie was never roboticized, and gained the original Roboticizer plans for a way to reverse the process.
- Call-Forward: With his younger self crushed over what happened to Uncle Chuck, Sonic assures him that someday he'll be back to his original state of mind.
- Foreshadowing: King Acorn is shown getting sucked into the Void, setting up his next appearance.
- Harmful to Minors: As revealed here, Sonic witnessed Uncle Chuck's roboticization when he was only four.
- Irony: After seeing the Roboticizer works as he desired, Robotnik thanks Chuck for inventing it and selects him to be next.
- It's Personal: This episode reveals that Robotnik's focus on Sonic may be due to a hedgehog that looked like him (actually was him) causing his left arm to be roboticized.
- The Promise: Before departing, Sally makes Rosie promise to never leave Knothole. When Sonic asks what that was about, Sally reminds him of how, originally, Rosie was ultimately captured in the forest and roboticized. As a result of this, history is slightly altered so that she still lives at Knothole.
- Secret Secret-Keeper: Rosie says she knew all along who the adult Sally really was.
- Set Right What Once Went Wrong: Thanks to tempering with the past, Sonic and Sally discover that one of Robotnik's ships is targeting the entire Great Forest, sooner than they anticipated. So they have to destroy it before it destroys the forest and thus Knothole, resulting in them being Ret-Gone. There is also the mission to save their younger selves before they are roboticized.
- Villainous Breakdown: Robotnik loses it after Sonic causes his left arm to be roboticized.Robotnik: Get that hedgehog. Get him! GET HIM!
- You Already Changed the Past: This episode reveals a time-traveling Sonic caused Snively's baldness, and also knocked Robotnik into the Roboticizer, resulting in his cybernetic left arm.
