Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Abner takes the locket from Helga at the end, Helga chases after him. In the next shot, they are shown running past the basement window of the boarding house, but that's impossible because they started running away from the basement window in the previous shot. (00:11:42)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: After Helga leaves the boarding house through the basement window at the end, when it shows a close-up shot of the locket in her hands, Helga's sleeves are way longer than they should be. (00:11:37)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Arnold and Grandpa are in the basement trying to pry open the locket, the tools on the workbench constantly rearrange themselves in various shots. (00:10:06)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: Helga's Locket: When Arnold is cutting a photo of Grandma in his room, there is nothing on his computer screen. Then, when Arnold starts to leave his room, a photo of Lila appears on the screen. (00:05:48)
Helga's Locket / Sid and Germs - S5-E7
Continuity mistake: When Sid decides to be a slob again, he picks up his frog and you can see that he has gloves on. When the following shot shows a close-up of the frog in Sid's hand, the hand holding the frog does not have gloves on.
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.