Part-Time Friends / Bio Square - S2-E19
Other mistake: Bio Square: While Phoebe and Stinky are telling the class about their science fair experiment, just as Phoebe shares that it was in honor of her hero, "I.P. Pavlov," watch as Stinky's eyes move off to the side of his head, then the animation layer of his eyes return to normal.
Arnold's Hat/Stoop Kid - S1-E3
Continuity mistake: When Grandpa is telling Arnold about how how he tried to cover his head when his hair falls out, the camera cuts back to him with his arm on Arnold's shoulder and Arnold has his hat on, even though the whole story is about him losing his hat.
The Aptitude Test / Oskar Gets a Job - S3-E9
Interviewer: You're kidding, right?
Arnold: No, it's not a joke, he really wants to work.
Interviewer: He's 38 years old, he's never had a job, and you expect me to hire him... as an X-ray technician? [Laughs].
Monkeyman! / Buses, Bikes and Subways - S5-E1
Trivia: The banana warehouse at the dock says "ROB RTSON" on top; Chris Robertson is one of the show's artists.
The List/Haunted Train - S1-E8
Question: Why did that boy steal Arnold's ball? Was that the whole reason he came to the park? He seemed awfully obnoxious and destined to ruin Arnold's day, just wanting more clarity. Thank you.
Answer: The episode doesn't really elaborate on who the kid was and what his motives were, so its pure speculation as to why he took it. Perhaps the kid could simply want a ball all for himself and decided to just take it, or was simply a rotten kid. The truth is the kid's motives are not important to the story other than it highlights Arnold was having a lot of trouble getting through the list.
Lummie ★