Due to this game being DarkerAndEdgier than the standard MascotFighter, heavy doses of NightmareFuel were inevitable.
* Polygon Man. [[spoiler:Everyone you defeated in Story Mode then became his minions, and now he makes you have to fight them again, only now, they are glowing purple with yellow eyes. And if you fail to beat him, he turns you into one of his own as well.]] Made especially disturbing if you're playing as someone cute like [=PaRappa=], Sackboy, or Spike.
** Heck, the boss battle in general: stuck in a purple battle arena with [[spoiler:Polygon Man taunting you as you fight your purple mutated rivals]].
** Actually, you only fight three opponents, and not all of them will be opponents you faced already; heck, you might not have faced any of them. Still, they are participants in this tourney, and the thought of beloved characters like Jak & Daxter, Ratchet & Clank, Parappa, or Sly Cooper being turned into mindless slaves for the Polygon Man is sure to make you at least uneasy.
* Isaac Clarke's default losing animation. Most of the other characters just look angry, upset or disappointed when they lose... Isaac, on the other hand, desperately claws at the ground as he gets dragged into an abyss, feet-first, by [[NothingIsScarier who knows what.]] The rest of his loss animations show him sinking to the ground, clutching his head as if he's going insane, and another shows Isaac just floating motionless in space. Then his loss animation on the results screen shows that all that's left of him is his helmet.
* Hearing your favourite characters scream as they are killed by a super [[CrossesTheLineTwice is kinda funny but painful at the same time]]. Isaac's in particular sound the most horrifying.
* When Little Sister first meets Sackboy in Sackboy's Story Mode. "Let's unzip him and see what's inside!" *shiver* The rest of the cutscene, however, is a CrowningMomentOfHeartwarming, but still manages to be a tad bit creepy too.
* Even though Heihachi's Lvl. 3 finisher is pretty ridiculous, [=PaRappa=] and Spike's terrified faces as they are strapped to the rocket is pretty unsettling, to say the least.
* If you listen closely to the background noise in the Dojo with the music off, you can hear some very graphic screaming (Men and Women) beside the MAWLR's blasts. Considering how lighthearted Parappa's world is, [[SugarApocalypse this can be quite chilling]]. You can also spot the machine through the window and feel its footsteps being fed through the [=DualShock=] 3 before the scene-change, meaning this has been happening all through Chop Chop Master Onion's rather fun lesson.
* One of Radec's loss poses is him clutching at a wound with his gun aimed at someone offscreen. Last time he took this pose, he ''killed himself.''
* During Fat Princess's ending, her kingdom is elated to see their princess return, but are a little disappointed that she hadn't brought back any cake with her. The narrator then tells us that the princess ''did'' bring something along with her to help her rule her land, and when he says this, the princess suddenly looks at the camera with a rather unsettling smile on her face, while glowing with the power she gained from defeating Polygon Man. It's [[SurpriseCreepy a bit unnerving]], especially since it ends with the implication that the power she obtained may have corrupted her.