Other mistake: Ms. Perfect: When the girls sabotage Lila's lunch, as Helga pours out Lila's milk from her thermos, the milk crosses an invisible line and disappears. (00:16:56)
Other mistake: Ms. Perfect: When Mr. Simmons tells the class, "I have a note from Lila's father," his right sleeve briefly turns green. (00:19:22)
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.