Due to a favorable accident on Odd's part, which consisted of spilling candy on the keyboard of Jeremie's Computer, Jeremie's materialization program for Aelita is finished, but since Jeremie has no idea how Odd got it to work, it is only good for one use. In turn, XANA possesses two bulldozers and sets them on the factory to prevent Aelita's materialization from taking place.
When trying to stop the attack, Yumi falls into the Digital Sea. To save her, Aelita gives up her materialization program, which allows Jeremie to bring back Yumi.
This episode contains examples of:
- Achievements in Ignorance: Odd manages to reboot Jeremie's program and fix it, simply by dropping candy on his keyboard.
- Attention Deficit... Ooh, Shiny!: Odd sits at Jeremie's computer, intrigued by the materialization program on the screen for a moment, then he notices the candy and goes straight for it.
- Back from the Dead: Yumi is revived at the end of the episode after falling into the Digital Sea, which ended up killing her.
- Big "NO!": Yumi when she arrives seconds too late to save Odd from being devirtualized. Ulrich has one too when he arrives a literal second too late to save Yumi from falling into the Digital Sea.
- Body Wipe: Ulrich's hand reaches for Yumi in the "Walking into Camera" variant.
- Bread, Eggs, Breaded Eggs: Jeremie tells Odd that he's "such a cosmic creep" for dropping candy accidentally onto his keyboard, but then calls Odd a genius for making the materialization program work, to which Odd asks if he's a genius or a creep? Jeremie replies that he's "a creepy genius," causing Odd to scowl.
- The Cameo: Jim's only appearance here is him sleeping just before XANA's attack. Still better than Sissi, who isn't even mentioned at all.
- I Let Gwen Stacy Die: As the gang briefly mourns the loss of Yumi (before realizing they can bring her back), Ulrich expresses how he feels solely responsible as "if he had been faster, she would still be here".
- It Only Works Once: Jeremie is unable to back-up Odd's program due to not seeing what exact code word he accidentally punched in, making it a one-shot use, which they use to revive Yumi at the end.
- Failure Is the Only Option: As only the sixth episode of Season One, it shouldn't really come as a surprise that Aelita isn't materialized at the end nor is Yumi killed off.
- Fate Worse than Death: It would seem the Digital Sea inflicts this on whoever falls into it, which ultimately happens to poor Yumi.
- Foreshadowing:
- Ulrich uses earplugs when sleeping; implied to be because Odds snores, judging by his shocked reaction. This foreshadows Ulrich being knocked unconscious by XANA crashing into one of the factory's poles. When Yumi gets him to Mission Control, he falls asleep again, causing Odd to quip that "he's not using earplugs" to fall asleep.
- When Jeremie criticizes Odd's performance on Lyoko, the cat boy quips that they should trade places. Cue a distressed look from Jeremie.
- For Want Of A Nail:
Fridge Logic turns to Fridge Horror quickly when you consider what may have become of Yumi had Odd simply not spilled candy on that computer keyboard... - Friend-or-Idol Decision: Though it's more like a "Girl-I-have-a-crush-on or best friend" decision, this episode shows shades of this; Save Yumi from permanent devirtualization (thus permanently killing her for good), or make Aelita a real girl. Aelita gracefully gives up her spot to save Yumi as she was part of the group's world already.
- Inconsistent Dub: A variation. In the English dub, Jeremie doesn't say his catchphrase at all this episode when making the return-to-the-past jump, though the visuals very clearly show him saying it. This is very odd, as the original French version had him say it, so it was likely an error in the dub that was never caught.
- Killed Off for Real: Yumi's fate after falling into the Digital Sea, luckily Jeremie is able to bring her Back from the Dead.
- No Plans, No Prototype, No Backup: Clearly done here for sake of the plot; Jeremie cannot save or backup the program, as he didn't see what combination of code the candy typing did to make it work, and it's implied he cannot back the program up without knowing how it all works.
- Suddenly Shouting: When Ulrich pulls his earplugs out and asks what Jeremie said, this exchange occurs:Jeremie: I said IT'S A XANA ALERT! XANA'S ATTACKING!
- Undead Tax Exemption: Discussed; an excited Jeremie wants to materialize Aelita as soon as possible, but Yumi and the boys immediately point out all the problems that it would cause. Aelita, as far as they know, has no parents, no birth certificate, and isn't enrolled at any school (the last point Ulrich doesn't consider too problematic though), therefore she essentially doesn't exist in the real world. Even Aelita thinks it's better to wait until they've made the appropriate preparations, which Jeremie reluctantly agrees with. Sadly, they don't get the chance to act the plan out before XANA makes his move.
- What Is This Thing You Call "Love"?: Aelita and Jeremie get involved in a late-night conversation about the senses, though while Aelita has some knowledge of human emotions, and knows what touching is at a basic level (it uses the brain, but not in the way Aelita knows), and reveals that she doesn't sleep, it surprises Jeremie that one of the things Aelita wants to try out when she comes to Earth is sleeping, touching things, and practice kissing, which leaves him a bashful, jabbering mess for a few seconds.note
- Worldbuilding: According to Aelita, virtual beings on Lyoko don't sleep, and according to Jeremie, Lyoko denizens have two senses instead of 5; seeing and hearing, instead of seeing, hearing, touching, taste and smell.
