!!Tropes for the movie
* BigLippedAlligatorMoment: The president's "eat lead!" bit, which interrupts the flow of the scene and doesn't really make sense in context. Which makes sense, since Colbert [[ThrowItIn ad-libbed it]].
** Also, the entire Axel F scene, which is basically there because it's [[RuleOfFunny hilarious]].
* CargoShip: B.O.B./Green Jello. A match made in mixers.
* CrazyAwesome: General Warmonger.
* CrowningMusicOfAwesome: The orchestral cover of Music/TheB52s' "Planet Claire'' that plays as the President prepares to make first contact.
* EnsembleDarkhorse: Oh, there's a LIST for this one.
** B.O.B. for the kids and the merchandise. Not really surprising he's the KidAppealCharacter; he's the silliest looking monster, and the funniest character.
** Dr. Cockroach hit it off with fangirls.
** And there's the president, where every moment involving him is one of the most hilarious things you'll ever see.
** Katie and Cuthbert, the OneSceneWonder [[GenderFlip role reversal]] teens who encounter the aliens early in the movie.
* ShipToShipCombat: The fandom is a bit split when it comes to who Susan gets paired with. Given the lack of TokenRomance within the film, many tend to gravitate towards Dr. Cockroach/Susan since he takes an active role in trying to reduce her size and they seem to converse the most (also, they're the only two monsters who used to be human). But Link/Susan has its share of fans as well, considering that Link's whole deal is that he chases beautiful babes anyway. God help you if you're on the fence.
* UglyCute: Pretty much all of the other monsters aside from Susan herself.
* UncannyValley: The stylized inhuman "Monsters" are a bit easier to watch than the actual humans.
* ViewerGenderConfusion: [[spoiler:Insectosaurus]]. The movie calls the monster [[spoiler:a "he"]], but a behind-the-scenes book lists [[spoiler:the monster as a female]]. This has lead to a BrokenBase amongst the fans of the movie as to which is truly canon regarding the monster's gender.
* WhatAnIdiot: Derek dumps Susan for the sake of his career without considering the worldwide fame their continued relationship would bring him, not to mention the millions of dollars in book deals and movie rights. Sure, he'd need a raincoat to have any hope of ever pleasing her, but it's still a very stupid decision from someone who's already been characterized as a selfish asshole. [[spoiler:He ''does'' put things together, sort of, when he forgives her and offers to take her back at the end. Of course mentioning that he was offered a network slot if he got an exclusive interview in the next sentence made Susan doubt his sincerity]]. Letting that detail slip only reinforced his stupidity.
-->'''Susan:''' Are the cameras running, sweetie?\\
'''Derek:''' Why, of course they are!
** It's more likely he lost her at 'I forgive you.' I mean, come on.
** Susan. After Derek dumps her, she looks so much like a kicked puppy.
** The monsters, after they scare off the party.
** Link. The poor guy gets his butt kicked ''several'' times during the battle against the robot probe, and even gets knocked out ''after it's already been defeated.''