The Aptitude Test / Oskar Gets a Job - S3-E9
Plot hole: Mr. Simmons asked that each student put their name on the test folders, but the folders already had names on them when he handed them out.
The Aptitude Test / Oskar Gets a Job - S3-E9
Plot hole: Mr. Simmons asked that each student put their name on the test folders, but the folders already had names on them when he handed them out.

Weird Cousin / Baby Oskar - S4-E11
Other mistake: Stephen Viksten is credited twice for voicing Oskar.

Freeze Frame / Phoebe Cheats - S2-E8
Trivia: Arnold's computer is made by Purdy Electronics; Joseph Purdy wrote the episode.
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 ★