* TheWoobie: Sam.
** Most of the Garde can qualify as this.
* JerkSue: Mark.
** You pretty much expect it to be aliens or magic, but when they actually explain it, it's kind of sudden.
** This is played for effect with the Mogadorians whose mouths are obviously not well suited for human speech, resulting in a mumble which sounds like baby talk.
** Pretty much anything uttered by the Mogadorian Commander.
* NightmareFuel: "And it wants to play with you too!"
** The appearance of the Mogs, especially the slits next to their noses which they apparently use to breathe.
* StrangledByTheRedString: It's explained that the alien race ''works like this,'' with your first love being for life. Number Four falls in love with Sarah within two days and apparently ''permanently.''There's a long scene of overly-flowery declarations of love delivered in a manner that would make ''[[Franchise/StarWars Padme and Anakin]]'' cringe.
** And then he hands her over to Mark the JerkAss at the end before riding off with Sam and Number 6.
* VisualEffectsOfAwesome: ILM were behind the special effects. Of course they're going to look spectacular.
* TheyWastedAPerfectlyGoodPlot: The movie could have been better if it were just Number 4 and Henri on the run from the Mogadorians