- The episode Wall of the Wild can be considered as the darkest and scariest episode in the series, as well as one of the most atrocious in the series.
- The Giant Spider that tried to kill Rodney.
- When Andy thought and doubted that Rodney had ran away from home (even though he was stuck in the wall during the time) and despite Mrs. Johnson's awkward attempts to comfort her son, Andy experiences a few daydreams of him disagreeing with Rodney for helping him and his father fix the air conditioner and then disavowing his friend that may be unsettling and/or horrifying to some viewers.
- The first daydream Andy had in Wall of the Wild may be a sepia-tone fantasy similar to Frankenstein about Rodney curiously asking him to help him and his dad fix the air conditioner and his bragging response for doing it on his own before the fantasy breaks into shards, almost seems not actually scary and mildly unsettling, but the second and last daydream Andy had later on was much more WORST, because of its reddish and hellish fantasy and it's similarity to Dracula, depicting on Rodney begging for merciful pleads to help him as a giant vampiric version of Andy disowned him harshly (complete with fire transitions), which would definitely be frightening to younger viewers and becoming one of the most nightmarish and horrific scenes of the entire show.
- The last daydream Andy had with a vampiric Andy disavowing a small merciful Rodney in a hellish nature, attributing giant size, fanged teeth, an evil grin, a vampire cape, and with one leg standing on a human skull.Rodney: (in daydream; mercifully) Please let me help, Andy. I just want to be of service. Pleeeeease?Andy: (in daydream; angrily) Hello!? You're a squirrel! You're nothing! You hear?! NOTHING!
- Stan, a recurring character in the series and the exterminator in the episode, has a dark and troubled past with the 'Talking Wallrat of Sumatra' (who defeated him, complete with the wallrat doing an Evil Laugh; despite his appearance looking not too scary and maybe hilarious for some), and also wants to hunt down and kill Rodney due to believing he is the 'giant sumatran wallrat' he encountered in his past adventure.
- One word: Puggo.
- Mr. J's nightmare of Rodneys in the episode The Endangered Species Twist.
- The bunny Archie and his evil villainous demeanors in the episodes The Trojan Rabbit and Bunny and the Beak.
- That face Mr. J makes to mock Rodney in "He Got Blame".
Nightmare Fuel / Squirrel Boy