About the characters

- Second episode in which Nicolas punches Herb.
- Yolanda is engaged and will soon be married.
- Yumi likes croissants.
- According to Jeremy, Aelita loves croissants with her hot chocolate.
- Odd says he’s gone out with all the girls in year 8 except for Heidi Klinger (plus Aelita and Sissi).
- We see in this episode a total of seven kisses. But the only “real” kiss is the one between Jeremy and Aelita at the end.

About errors

- The lift is at the factory entrance just before the polymorphic clone calls it up.
- Herb’s hair is entirely black when he asks what Ulrich has that he doesn’t.
- After Heidi asks why Jeremy kissed her in front of Odd, her purple pants disappear.
- Jim’s rolled-up sleeves are red instead of black when he sees Yolanda (the polymorphic clone) arrive.
- When Odd is shown kicked into a pile of books by the fireplace, his undershirt is missing from his torso.
- When the polymorphic clone approaches Jeremy, we can see Odd’s icon on the computer screen but he wasn’t virtualised in this episode.
- Just before Aelita enters the Code Lyoko, her outfit is reversed.
- The factory microphone disappears from Jeremy’s ear when he tells Ulrich he’s sent the Overbike and when he’s thrown by Yumi’s clone, and in one shot it’s in his right ear.
- At the moment when the polymorphic spectre arrives at the factory, we hear it panting, which shouldn’t be the case because spectres don’t breathe.

About the series

- French title: Mon meilleur ennemi

- In the original French, this episode was previously titled “Ennemi intérieur” (“Enemy Within”), then “Diviser pour régner” (“Divide and Conquer”) and finally “Mon meilleur ennemi” (“My Best Enemy”).
- First appearance of the polymorphic clone.
- First mention of the name of Ulrich’s vehicle.
- Nicolas hits Herb exactly as in episode 35, “The Chips are Down”.
- Ulrich says he never kissed Sissi, however he did in episode 19 “Frontier” and Sissi kissed him in episode 41 “Ultimatum”.
- Odd: “That doesn’t make any sense, he can’t control us!”
Odd makes an allusion to episode 31, “Mister Puck” when XANA had tried to XANAfy him and Ulrich but didn’t succeed.

About references

- Allusion to the quote “Divide and conquer” which is directly linked to the high political spheres in the dictatorial systems like Nazism or Stalinism…

- Mr Fumet (history teacher): “Ulrich, uh, when did Gallieni die?”
Joseph Simon Gallieni was a French soldier in the late nineteenth century.