Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: When Helga chooses Phoebe to be the new hall monitor, as Phoebe starts walking to the stage, she is briefly layered behind the boy sitting behind her, and she is layered over Joey and the boy sitting next to him. (00:02:31)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: Helga tries to convince Phoebe that being hall monitor is the greatest job, with plenty of perks. Just as Helga says, "I couldn't let this job go to anyone; I picked you," Helga's hand is on Phoebe's shoulder, and part of Phoebe's shoulder is missing. (00:03:10)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: After all the kids run into Phoebe, when Sid runs past her and her hat comes off, we can see that the hair above her scrunchie is yellow instead of black as it should be. (00:03:44)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: During detention, the class helps Phoebe realise how much she has changed. When Helga wipes the window so Phoebe can see her reflection, in the first shot, Phoebe's reflection is not backwards as it should be. (00:10:45)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: In the credits, actor Elliott Gould's name is misspelled as "Elliot Gould." (00:22:59)
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: In the credits, Justin Shenkarow is credited twice for voicing Harold. (00:22:59)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Grandpa runs out of Arnold's bedroom to get the S.S. Gibraltar, Arnold's hair is layered over the door when it should be behind it. (00:03:42)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Arnold, Gerald, and Grandpa are first shown at the Tour de Pond race, their ship is not sitting on the sidewalk, but rather on the edge of it, which makes it look like it’s floating in mid-air. (00:05:02)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Rex first approaches Arnold, Gerald, and Grandpa at the Tour de Pond race, as he says, "Are you two going to race that... put it on display?", Arnold's shoes are white instead of black, as they should be. (00:05:25)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Arnold and Rex's boats get stuck together during the first round, there are two shots of Sid and Phoebe at the stand. They are supposed to be sitting in their chairs, but they are misplaced too far to the left of them in these shots. This is shown again at the start of the final round. (00:07:13 - 00:08:45)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Arnold and Rex's boats get stuck together during the first round, Sid says, "Yeah, plus they're stuck together." In this shot, the microphones are hanging from the banner, and the blue bell is hanging upside down on the side of the stand; one of the animation cels has been placed upside down. (00:07:18)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Rex's grandfather walks up to Arnold's Grandpa at the end, Arnold's left side hair has five spikes instead of four like it should. (00:11:12)
Tour de Pond / Teachers Strike - S2-E18
Other mistake: Tour de Pond: When Arnold and Rex are talking to each other at the end, when the camera zooms out, Rex's legs are briefly cut off before appearing mid-shot. (00:11:41)
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.
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: After Nick Vermicelli says that the parade float is a total mess, as Arnold says, "It's not a mess," the background is of the school hallway, not Arnold's garage. (00:05:28)
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: When Bob asks the kids who wants to ride on the float, Arnold says to them it's great the way it is. In one shot, Iggy's hair is incorrectly coloured black instead of brown. (00:05:52)
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: After Nick talks about redesigning the parade float, Bob asks the kids who wants to ride on the float. Arnold then tells them it's great the way it is, and when the kids start saying, "Me! Me!", there is an animation glitch where part of Robert's head and hands get stuck in the air for about a second. (00:06:01)
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: After Bob says, "Now this float has to scream 'beeper' at the top of its lungs!", as he walks away from Arnold and Helga, Joey is mistakenly drawn with white skin, blonde hair, and an orange shirt. (00:06:31)
Runaway Float / Partners - S2-E20
Other mistake: Runaway Float: When Arnold tears apart the big beeper on the parade float, the float's platform is missing, which makes it look like Bob and Nick are on the road. This happens again after Arnold stops the float, which makes it look like Bob and Nick are floating as a result. (00:10:19)
Answer: The show is based in present day times. Plus most cars aren't old fashtioned, I recall seeing a limo and not to mention a cherry picker, etc.