Every once in a while, Nickelodeon gets mega-dark with its cartoons. “Hey Arnold” spent most of its time being a light-hearted story of a boy growing up in the big city, but then turned on a dime to give us genuinely terrifying episodes.
Case in point: “The Haunted Train.” Arnold’s grandpa tells him and his friends the legend of Engine 25, a train whose engineer went mad and drove it off the tracks. Every year, it returns to pick up new passengers, blinding victims with a hypnotizing white light and driving them straight into the underworld. A little spooky for children, yes? Perhaps even traumatizing?
Well, later that night, Arnold and his friends end up falling into the clutches of the sinister engineer, and only manage to escape the ghostly train at the last minute. The most unsettling aspect of the episode is that, although the horror starts to deescalate when Arnold suggests that Grandpa probably made up the story and that the following action was all in their imaginations, the final shot shows the engineer singing as he rides his haunted train, implying that it was all real.