- Mr. Cat, full stop. Something about that cat just isn't right. He's an Ax-Crazy sadist who has engaged in criminal activity and is not afraid to kill. It's especially disturbing when you consider the fact that he's a kid who's less than 13 years old.
- Even his introduction in the intro is a bit nightmarish - he crosses out an image on his list of things he wants to do (or, more likely, already did) to Quack Quack, then he is shown on a dark background, with fire, dark clouds and weapons everywhere. And then, he lets out a laugh...
- Kaeloo transforming into a giant monster is especially scary when you consider that said giant monster's actions are beyond her conscious conrol.
- Kaeloo and Mr. Cat's obsession with each other.
- For Mr. Cat, this manifests as him slowly becoming a Stalker with a Crush who spends his every moment thinking about Kaeloo.
- For Kaeloo, this manifests in an insane desire to keep every single person who Mr. Cat could even possibly develop a crush on, including Bad Kaeloo - the manifestation of her own subconscious mind - far, far away from him; as far as Kaeloo is concerned, Mr. Cat is hers and hers only.
Let's Play Magicians
- Mr. Cat dancing around singing "la, la, la, cute little ducky wucky" with a huge smile on his face... while stabbing the "ducky wucky" in question (Quack Quack) with a medley of sharp objects and weapons.
Let's Play Hopscotch
- Quack Quack gets sent to Hell because of Mr. Cat's hopscotch game and returns as a demon.
Let's Play Trap-Trap
- The way Quack Quack acts in this episode. The crazed, hungry expression on his face, the way he attempts to cannibalize Kaeloo and Stumpy, and most of all, him eating half of Kaeloo's brain by the end of the episode.
Let's Play Hide 'N Hunt
- In an attempt to anger Kaeloo to the point of transforming, Mr. Cat threatens to kill Stumpy if she doesn't. And Kaeloo refuses to do it because "anger is a negative vibe", even though her friend's life is on the line. And there's this little line we get from Mr. Cat as a result:Mr. Cat: I'm going to decorate the walls with lumps of squirrel...
Let's Play Danger Island Survivor
- In a game where Your Mind Makes It Real, it works so well that when Mr. Cat pushes Quack Quack on the ground and yells that it is a precipice infested with alligators, his insides appear to have been eaten for real, and Stumpy's feet catch fire when he steps on fake lava.
- The reason Mr. Cat caused the horrible incident above to happen to Quack Quack? Because he was envious that Kaeloo said Quack Quack was her "best friend". Talk about being possessive.
Let's Play Peace, Man!
- Mr. Cat throws a mallet at Quack Quack. Kaeloo says he lost, since the aim of the game they're playing is to not get angry, but he says that that was just a "little love tap"... then the background behind him bursts into flames and he menacingly says "You'll know it when I get angry."
- The end of the episode. After Kaeloo transforms, instead of beating Mr. Cat up, she decides to kiss him. Mr. Cat clearly doesn't want to, and he tries to escape, but he ends up getting dragged off screen before the usual Smash to Black. The next scene, which takes place some time later, shows Mr. Cat sitting on the ground, hugging his knees and looking absolutely traumatized by what just happened, implying that she actually managed to force the kiss on him anyway.
- Not bad enough? Kaeloo - regular Kaeloo, detransformed - puts both her hands on his face, forces him to look her in the eye, and asks if she can do that to him again with a huge smile, as if she hasn't even realized that her actions were wrong because "kissing's not violent" - or worse, as though she's thoroughly enjoying her victim's discomfort.
Let's Play Scaredy Cat
- Stumpy raises the dead and causes a Zombie Apocalypse. When Quack Quack and Bad Kaeloo also get turned into zombies, Mr. Cat is forced to fight all the zombies by himself.
- At the end of the episode, Mr. Cat puts an arm around Stumpy's shoulder and they walk off into the forest. As they walk away, Stumpy turns around and shows the audience his glowing, yellow eyes, referencing Thriller. Long story short, Mr. Cat is walking into a forest alone with a zombie.
Let's Play Babysitting
- Mr. Cat mentions almost being drowned as a baby.
- Near the end of the episode, Mr. Cat tries to rape Kaeloo. Sure, he fails, but that doesn't make it any less scary.
Let's Play Cowboys and Indians
- Mr. Cat ties Kaeloo up and hangs her over a fire before sending Stumpy and Quack Quack a message: "Frog taken hostage, execution imminent. Free barbecue and salad bar!"
Let's Play Time Travel
- The episode's plot is that the cast go back in time to 19th century London, where it's dark and foggy, to track down a serial killer.
- Quack Quack and Stumpy getting attacked with the former being decapitated and the latter being skewered with a corkscrew. Unlike the show's usual Amusing Injuries, these are absolutely terrifying since we don't see the attacker, and it's very dark and foggy. The implications that Mr. Cat did it aren't much better either...
- Near the end of the episode, Kaeloo takes her friends to the year 6000 and they find themselves in a white, empty void where they've become "spirits of kindness and wisdom". While that doesn't sound so bad, that place is completely empty, with only Kaeloo, Stumpy, Quack Quack and Mr. Cat being present. When Stumpy asks Kaeloo what kinds of games are they going to play in 6000, she just responds, in a Creepy Monotone and a bit of a psychotic look on her face, with "Nothing. No console, no TV. We exist.". Stumpy naturally responds to this by returning to the time machine.
Let's Play Me-Me-Nopoly
- There's something unnerving about the way the sky turns red when Mr. Cat manages to Take Over the World...
Let's Play Art Class
- Mr. Cat pulls off a Nightmare Face, complete with bloodshot eyes, Slasher Smile and pointed claws.
- When Stumpy blows his own head off with a bazooka, Mr. Cat comes up with the idea to use his corpse in an art exhibit.
Let's Play Paranormal Stuff
- Quack Quack getting possessed by the ghosts of the yogurts he ate in the past.
- At the end of the episode, Stumpy asks the audience what would happen if the ghosts of all the acorns he ate returned to haunt him. The camera then pans out to show Stumpy surrounded by several ghosts...
Let's Play Astronauts
- A minor example. When the main four are traveling through space, Kaeloo points out a meteorite to the others. After they leave, the meteorite hits a random planet near them and vaporizes it.
- Everyone's behavior (except Stumpy's) becomes more and more unsettling after they enter the Alternate Universe, and it's especially creepy during the part when Stumpy tries to escape from them.
Let's Play Tennis
- Mr. Cat throws a bunch of knives and other sharp objects at Quack Quack, who hits them back with a tennis racket. The sharp objects impale Mr. Cat... and he starts laughing. Normally, someone who just got severely injured like that would be showing some sign of pain, but Mr. Cat just stands there laughing.
Let's Play Figurines
- Stumpy makes a Deal with the Devil, turns himself into a witch doctor, and gets voodoo-like control over everyone else. At the end of the episode, he is sent to Hell.
- The way Kaeloo acts when Mr. Cat, disguised as a police officer, tries to interrogate her. She has a bizarre, creepy expression on her face and the part where she rotates her head all the way around is just plain terrifying.
- Mr. Cat kills himself after becoming extremely annoyed with Stumpy's stupidity and the audience gets to see his lifeless, hanging body. Sure, it's Played for Laughs and he comes back in the next scene, but it's still disturbing to see one of the show's main characters kill himself onscreen for such a trivial reason.
- Ki Ce Ka Raison itself; the game show treats its contestants horribly and freaks them out. By the end of the second question, Mr. Cat is cowering behind his buzzer, and the final question has him pass out.
- The final question. Not the question itself, but the way it is asked: Mr. Cat is surrounded by a ring of fire and Bad Kaeloo threatens to beat him up if he doesn't answer it correctly.
- Stumpy trying to cannibalize Kaeloo when they are stranded on an island.
- Pretty finds Mr. Cat and offers to give him mouth-to-mouth. He declines, since he is absolutely fine, so she knocks him out with a baseball bat and the last thing we see before the scene switches is a close-up of her face slowly moving towards his, with her creepily drooling.
- Quack Quack eating the cannibal yogurts.
- At the end of the episode, Mr. Cat and Pretty are still stranded because the others forgot to rescue them. Pretty has clearly gone crazy, to the point where Mr. Cat is screaming for help to get away from her.
- At the end of the episode, Kaeloo, Stumpy and Quack Quack chase Mr. Cat around with weapons. It's funny until he yells that he's not indestructible...
- We finally find out where Mr. Cat buys his weapons - the internet. You know, that place that literally anyone in the world can access with a computer or phone.
- Mr. Cat doesn't take very well to Quack Quack leaving Smileyland. In the absence of someone to torture, he almost kills Stumpy with a chainsaw.
- Due to the events of the previous episode, Mr. Cat is stuck in prehistoric times. How do he others realize this? By accidentally coming across a fossil, which Quack Quack identifies as one of Mr. Cat's bones. Which means, he actually would have died had they not rescued him.
- Bad Kaeloo attacking Mr. Cat with a pair of sharp scissors offscreen.
- Kaeloo the creepy undertaker, period. Her behavior is enough to freak out even the Desperados, and at one point she even locks them up in coffins.
- Mr. Cat sets a building on fire with Quack Quack inside. This isn't that bad, since he's Nigh Invulnerable. But then, Stumpy, who is not indestructible, rushes into the building to save Quack Quack, and they both get stuck because the others are too busy to help them.
- As pictured above, Kaeloo becomes scary as heck when she undergoes Sanity Slippage.
- The way Mr. Cat is portrayed in Kaeloo's intro to the episode, which she animated herself. He starts out as a disembodied pair of glowing eyes and a set of sharp teeth in a pitch dark background, which is suddenly illuinated by Mr. Cat bursting into flames, turning him into a flaming, flying, supernatural being with Glowing Eyes of Doom.
- When Mr. Cat picks up one of the mini-Mr. Cats, it gives him various horrible threats including disembowelment.
- Stumpy almost erases the rest of the main four from existence and then proceeds to take over the animation studio making the show.
- At the end of the episode, after convincing Stumpy and Quack Quack that cats are the best species in the world, Mr. Cat arranges for them both to get plastic surgery to look just like him, "turning them into cats".
- Vampire Stumpy being destroyed by sunlight. Unlike Vampire Quack Quack, it's shown in a more painful-looking, slower manner and is disturbing to watch, even though it's Played for Laughs.
- Mr. Cat getting an allergic reaction and exploding.
- When Mr. Cat wants to prevent Stumpy from telling Kaeloo an embarrassing secret, he repeatedly slaps him in the face with a pair of underwear to torture him... "because [he] lost [his] chainsaw". Yes, Mr. Car just implied that he would be willing to brutally murder Stumpy with a chainsaw to prevent him from ruining Kaeloos opinion of him.
- At the end of the episode, when the main four find out that they were never fired and that Olaf was playing a "joke" on them, Kaeloo says that since Olaf wanted to "play" with them, they now have a new friend to play with. She winks at the others, who realize that she means they should 'play" with him main four-style... which involves extreme violence and abuse. The episode ends with them staring at him with psychotic smiles. The audience is left to imagine what the main four will do to him now...
- In one scene, Quack Quack and Mr. Cat are sword fighting and Quack Quack manages to knock Mr. Cat out. And as he's on the ground, Mr. Cat starts... laughing, in a really psychotic and menacing manner. He then pulls out a bazooka and shoots Quack Quack. Worse yet, it actually turns out that he managed to kill Quack Quack.
- The whole "Zumba with Friends" scene where Mr. Cat is forced to do an Involuntary Dance with Kaeloo, Stumpy and Quack Quack at the end was Played for Laughs, and it actually seems funny until you realize that Mr. Cat is actually being brainwashed into being a nice, happy, friendly kid.
- Stumpy and his clones destroy Mr. Cat's car, leaving nothing but the steering wheel, with him inside. How do they do this? By driving a bunch of other cars into his. Mr. Cat survives all of this, but is left traumatized and shaking all over.
- Mr. Cat stalking Kaeloo in the darkness since he, being a cat, can see in the dark and she can't, while saying "I can see you..." and following her every move. It gets so bad that he manages to traumatize her into becoming afraid of darkness.
- Quack Quack undergoing Demonic Possession.
- Once the gang manage to exorcise Quack Quack, the demon starts flying towards them, announcing that it wants to Take Over the World, while they cower behind each other in fear. Olaf shows up and calmly makes his robot Serguei destroy the demon, since he thinks he should be the one to dominate the planet. As if the demon wasn't bad enough, we now know that the lunatic bent on becoming the world's emperor is capable of building technology to kill demons that would scare even Mr. Cat, who has had experience with zombies, ghosts and other paranormal elements.
- Pretty turning into a tentacle monster.
- While Pretty's harassment of Mr. Cat was always slightly disturbing, the way she does it as a tentacle monster is horrifying.
- The giant three-headed sheep.
- Unlike the posters for the previous seasons, this one actually shows the characters in action; Mr. Cat has his mallet raised, facing the dark forest with a glare, ready to fend off who knows what.
- Part of the chaos that ensues because of the magic involves Bad Kaeloo turning into a giant monster and swallowing Mr. Cat.
- The nightmare Mr. Cat has at the end can be just as unsettling to the viewers as it is to him.
- It turns out that Mr. Cat has been killing people other than Quack Quack, who aren't immortal.
- If the show were to ever get canceled, the main four would end up broke and starving.
- "All of this... is Mr. Cat's fault."
- Quack Quack finds out that he had biological siblings who abandoned him as an egg. While he's still suffering from the trauma of figuring this out, Mr. Cat cheats at the lottery, gets rich, and ditches the main four to go live a happy life on his own without even saying a proper goodbye. This act of betrayal utterly breaks him and we see the usually easygoing, good-natured, friendly Quack Quack, of all people, with an expression of pure rage and bitterness which wouldn't look out of place on someone like Mr. Cat.
- One of the stories in Volume 1 has Quack Quack get bitten by insects. Since the duck is basically a walking science experiment, the insects mutate into giant monsters and start trying to attack the main four.]]
- During a power outage, Quack Quack realizes that the fridge will stop working and his yogurts will get spoiled. How does he react? By callously forcing Stumpy into a machine which electrocutes him in order to keep the fridge running. Kaeloo is justifiably horrified by this. If the mere idea doesn't horrify you, Mr. Cat says that even he wouldn't be able to do something like that.
- Mr. Cat and Stumpy need Bad Kaeloo's Super Strength to help them remove the shells from nuts. In order to access that Super Strength, they need her to transform. So what do they do? They give her detailed descriptions of what they'll do to Quack Quack if she doesn't agree, such as "I'll rip apart his stitches so I can see what's inside!"
- While this kind of behavior is normal for Mr. cat, it's frankly disturbing to see Stumpy join him, especially when he gets a crazed look in his eyes and proclaims that he will decapitate Quack Quack.
- While Stumpy and Quack Quack are taking a bath, Kaeloo accidentally scares them by telling them about all the germs and dirt that they need to get rid of. They try to scrub themselves clean so vigorously that they end up Stripped to the Bone.