
Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: At the start of the school assembly, when Principal Wartz thanks Helga for her month as hall monitor, Wartz's right arm is atop the lectern, with his fingers over the lectern's front edge. As Wartz gestures toward Helga with his right arm and hand, the fingers of his right hand oddly remain over the lectern's front edge. Then, after Helga announces she may volunteer again, the audience groans, and in the next shot facing Wartz, he has four hands at the lectern's edge. (00:01:35 - 00:02:00)

Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: When Helga is deciding on the new hall monitor and it shows a shot facing the crowd, many kids sitting in the back are faceless. (00:02:20)

Hall Monitor / Harold's Bar Mitzvah - S2-E15
Other mistake: Hall Monitor: When Helga chooses Phoebe to be the new hall monitor, as Phoebe is walking to the stage, Iggy's hair is incorrectly coloured black instead of brown. (00:02:30)

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)
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.