About the characters

- First time Aelita dies.
- Mr Delmas claims to have been working for 30 years as a principal.
- Only episode in which Yumi and Ulrich spar outside of a class run by Jim.

About errors

- The red halo of the activated tower disappears in two shots.
- We see during one scene that Ulrich has Yumi’s phone, which is red…
- The factory microphone disappears from Jeremy’s left ear in one shot.
- The factory computer shows three green icons instead of two plus Aelita’s (yellow) in one shot.
- When the factory computer shows “Ulrich vs Krabe” we can see three Krabes when there’s only one.
- When the principal announces to all the students that they need to leave the buildings, we see Emilie in class with Ms Hertz and in the next shot, she’s outside.
- Odd’s pants are entirely the one shade of purple in 7 shots and they’re entirely the darker colour when Jeremy explains how he got the idea of materialising the hair and after he says what happened to Sissi.
- The mouse pad for Jeremy’s computer disappears when he explains about the bug in Aelita and when he turns the screen so Aelita can’t see what he’s doing with Kiwi.
- When Yumi says she hopes Jeremy finds the solution before XANA attacks again, it’s Ulrich’s voice we hear instead of Yumi’s.
- When Jim mentions that he’s been searching for Kiwi for ages, we’re meant to hear Kiwi barking because of the ultrasound being used again. Instead, we hear nothing, and Jim appears to suddenly think of the dog randomly while observing the damage to the ceiling.
- The dorm hallway floor keeps changing texture from flat lino to planks of wood.

About the series

- French title: D’un cheveu (this title didn’t translate well into English, so they chose something completely different in the end)
- Original English title: By a Hair's Breadth

- Second time we see Sissi’s diary.
- Jim: “The dog! I’ve been after him for a long time!”
Jim makes an allusion to episode 3 “Holiday in the Fog” when Kiwi woke him up in the middle of the night.