Mud Bowl / Gerald Moves Out - S2-E9
Revealing mistake: At the lunch room, the 5th graders threaten the 4th graders again. Gerald starts talking to Arnold. He and the dark-haired girl to his left are both noticeably overlaid onto the table, not behind it. About 20 seconds later, the same shot is back and they're behind the table as they should be. (00:06:00)
Mud Bowl / Gerald Moves Out - S2-E9
Continuity mistake: When Gerald catches his little sister destroying his cassette tape, the book she is wrapping changes color from blue to green. (00:12:30)
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.