
The Big Scoop / Harold's Kitty - S2-E3
Revealing mistake: Harold's Kitty: When Arnold kicks the ball during the kickball game, he starts running, and he is layered over Helga, even though he is supposed to be behind her. (00:12:20)

Helga's Boyfriend / Crush on Teacher - S2-E14
Revealing mistake: Helga's Boyfriend: When Arnold walks up to Helga to tell her that Stinky loves her, he asks if he can talk to her about something, and in the shot of Helga, there is a line at the bottom of the screen going through her legs, cutting them off. (00:08:04)

Runaway Float / Partners - S2-E20
Revealing mistake: Runaway Float: When Arnold and Gerald are watching the parade, Arnold turns his head to look at the marching band. When he looks away from it, his left eye doesn't move, and it stays visible in his hair for the remainder of the shot. (00:07:51)
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 ★