* BigLippedAlligatorMoment:
** At one point Mike fights a GiantSpider in the basement, killing it by flooding the basement and electrocuting it. But when the bad teenagers steal the Goo moments later, there is no water in the basement, nor is there any sign of the spider's corpse, and the whole incident is never mentioned again.
** When Genius is trying to find a chemical that will reverse the growing effect, his mixing of liquid chemicals creates a crawling worm that goes down a drainpipe. Genius stares in awe, and then shrugs and says, "Back to the drawing board." It isn't explained how he could create a living creature, and it's never referenced again, and has no impact on the events of the movie.
* FridgeHorror: The teens all end up cooking and eating the giant ducks — which have very recently eaten the Goo. Now, like snake venom, one can assume it cooked out in the process — except that can you be sure? Gigantism aside, the chemicals used to make the goo could become toxic under heat. Not to mention the effort it took to kill and prepare two giant ducks.
* {{Padding}}: A good chunk of the runtime is taken up by musical numbers that have little to nothing to do with the main story. Though in fairness, Gordon did manage to find some comparatively decent performers for said musical numbers, meaning they actually end up being one of the main redeeming qualities.
* RetroactiveRecognition:
** Yes, that is indeed [[https://youtu.be/3E-Zrg9CB_Q?si=FGOZl7qeyC0pqSvi Toni Basil]] dancing for the wayward teens' amusement as a distraction while the other (normal-sized) teens attempted [[spoiler: a rescue of the sheriff's daughter]].
** Why yes, [[Creator/RonHoward Genius]] would become of the most recognized directors in Hollywood.
** You might recognize Joy Harmon (Merrie) as "Lucile", the girl washing her car in front of the chain gang in ''Film/CoolHandLuke''.
* SoBadItsGood: The movie has a much more tongue-in-cheek tone than most of Gordon's other films, and this combined with more than a little unintentional hilarity from the bad effects and complete lack of any grasp on how teenagers actually behave makes it ideal ''[=MST3K=]'' fodder.
* SpecialEffectFailure:
** The life-size props for Fred's legs are extremely thin and badly-proportioned, and look ridiculously hairy in comparison to the actor's actual legs. It's almost like the filmmakers spent most of their time and money on the life-size version of Merrie's torso (which, for some [[{{Fanservice}} inexplicable reason]], looks a lot more convincing by comparison), and then threw together Fred's legs as an afterthought.
** The rear-projection effects used to depict the giant teens are seriously unconvincing. Gordon may have been able to just about pull them off in black-and-white when he was making ''Film/TheAmazingColossalMan'' and ''Film/WarOfTheColossalBeast'', but doing said effects in color was clearly a step too far.

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