3. Did you ever notice in the episode “Weighing Harold” that there’s a direct reference to SpongeBob SquarePants?
This episode aired on April 7, 1999, which was about a month before SpongeBob SquarePants debuted its pilot episode on May 1, 1999.
5. In that very same episode, the powers that be over at Nickelodeon hit us with another easter egg: A CatDog reference.
CatDog was on Nickelodeon for about a year before this nugget appeared in “Weighing Harold,” but it’s still cool to see the creators of Hey Arnold! reference other Nicktoons by having them appear in other “worlds.”