- Adaptation Displacement: Chances are, if you mention this movie to someone, they're going to think of the Eddie Murphy one without realizing that the first version was in the 1960s.
- Big Lipped Alligator Moment: The scene in the original where Dr. Kelp's formula initially goes horribly wrong and turns him into a monster. It never affects the plot at all since afterward he becomes Buddy and is never brought up again.
- Hilarious in Hindsight:
- In the 1990s version, Sherman Klump adopts a reassuring motto from fitness guru Lance Perkins: "Yes, I can".
- It's also the catchphrase of Bob the Builder.
- Dean Richmond gets raped by a hamster in The Klumps. 1 year later, he becomes a principal in Max Keeble's school, where the titular character spikes his cologne with Pheromones causing various animals to try the same thing to him.
- Idiot Plot: In The Klumps, there was literally no reason Sherman couldn't tell Denise what was going on.
- "Denise! I spliced my genes that removed an alterative/thinner version of me and now he's walking around trying to steal my formula and all the while I'm getting stupider!" Doesn't exactly sound reasonable on face value.
- Nightmare Fuel: After Sherman proposes to Denise, they go out to see the original version of the movie Cape Fear, where they hear an obnoxious guy smoking a cigar and laughing too loud for them to enjoy the movie. (Which is an homage to the 1991 remake, ironically enough.) When Sherman politely ask him to stop, he turns around to reveal himself as Buddy Love. This gives Sherman the most epic Oh, Crap! look on his face. The music in the scene makes it even more scarier than funny.
Buddy: Just when you thought it was safe to go back to the theaters! HELLO, FATASS! (laughs maniacally)
Buddy: Sherman!!!!! SEE YOU SOON SHERMAN!!!!! SHERMAAAAAAAN!!!!!!
- Later on he starts to harass Sherman and Denise. At first Buddy, simply just wants what he claims is, his share of the youth formula, but when Sherman says no, he vows to destroy him there. It's all supposed to sound funny and over the top, but due to Eddie's delivery he comes across more like a deranged stalker out for blood.
- The previously mentioned scene from the 1963 version where Kelp's formula fails and transforms him into a monster before he becomes Buddy. The creepy music and lighting, Body Horror he goes through, and his hallucinating his bird with the Dean's head mocking him for his failure are all guaranteed to cause a few nightmares to any young kid who happens to watch the film.
- No Yay: The hamster and Dean Richmond, who both hint at being interested in continuing their relationship.
- The Scrappy: Buddy Love is smooth and cool — and an obnoxious girl-chaser.
- Sequelitis: Nutty Professor II: The Klumps wasn't as good as the first.
- Signature Scene: In the remake, Ernie Klump, Jr. flexes his muscle with his mother clapping and chanting "Oh, Hercules! Hercules! Hercules! Hercules!"
- Squick: "You know Mike Douglas used to make me moist when I'd watch his show?". Cletus Klump gets an understandably cringe-inducing reaction at hearing Grandma fantasizing with hooking up with men literally half her age (not to mention being accompanied by the oh so pleasant mental image of 100-year-old wet vagina) and proclaims that he wants to take the old bird out of her misery.
- Every scene involving Buddy and Grandma Klump in the second movie. Buddy finds out that Sherman's hiding the Youth formula at his parent's house. So naturally he tries to break in to get it. However what he doesn't know was that, his breaking and entering was in the middle of Denise's bachelorette party, where Granny hired a stripper. Granny mistakes Buddy for the stripper and Buddy tries to charm his way out like before, only for it to work too well, causing her to be infatuated with Buddy not knowing he's part of Sherman's split personality. Buddy finally gets the Youth formula and is about to make his escape only for Granny to show up and strip naked, to Buddy's Horror. (Luckily, we don't see what buddy sees.) She allows him to leave if she at least lets her kiss him. To which Buddy agrees, thinking he's gonna get a peck on the cheek. Instead he gets an open mouth, mouth toothless long tongued frencher from Granny instead. Cue Buddy running out of the house to find the nearest bushes to puke in....and crying afterwards.
- Tear Jerker: The scene in the first film when Sherman is being picked on by the comedian Reggie. We pan into Sherman's hurt face and sad music plays. Anybody who was ever bullied would know what that feels like.
Denise (in tears): Sherman, what is my name?Klump: "... Pretty... lady?"
- His binge eating after that is also incredibly sad. He's turning to Comfort Food after his failure of a date and, judging by the tears in his eyes, it's not helping.
- In the second film, when getting rid of Buddy turns Klump (apparently) irreversibly into a ditz, the now dumber (and amnesiac) Klump is the reason viewers need a tissue supply when watching the movie. And when he sees his love interest for the first time after that happens...
- The look on Cletus' face is also heartbreaking.
- Values Dissonance: In the original, a teacher is romantically interested in one of his students.
- The remake has Klump falling for a graduate student who's teaching her first class, which softens the implications.
- The Woobie: Professor Klump. Comedic as the remake is, it does also show how his obese situation is affecting his life negatively. His Amazingly Embarrassing Parents don't help, either.