Nightmare Fuel / Prehistoric Park

• It's telling that in a show that includes predators to the likes of Tyrannosaurus rex, Deinosuchus, and Smilodon, it's the Pleistocene human hunters in "A Mammoth Undertaking" that are presented as terrifying. We hardly ever see them, but Nigel is all too aware they are stalking him and Martha to finish their hunt. And unlike the wolves and hyenas, he can't see them coming with their lack of eye-shine.
  • The dead Mammoth, all those spears sticking out of its body was a very unpleasant sight. Also, it's implied the poor creature did not die quickly or painlessly.
• The fates that Nigel typically saves a handful of animals from.
  • The literal end of the world when the K.T. meteor collides with earth, with Terrance and Matilda just barely avoiding the blast by following Nigel through the Time Portal.
  • The Volcanic eruption and ash cloud that Nigel just manages to save a herd of Titanosaurus and Microraptors from.
  • The huge forest fire that Nigel and a bunch of prehistoric insects barely escape from (with help from Bob and a Titanosaur).
  • The gathering predators (including the aforementioned prehistoric human hunters) that Nigel and the crew protect Martha the mammoth from.
• The mass-breakout in episode six. After a stowaway Troodon startles Bob, he swerves his vehicle, spooking the Titanosaurs into a stampede that takes out a significant amount of the park's enclosures, letting the animals loose. Considering there were animals like the Elasmotherium, Terror Bird, and Tyrannosaurus rex among the escapees, it's a miracle that nobody was killed.