Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: At the movie theatre, Lulu is shown sitting in the seat to the right of Arnold. Then, when Hilda goes to sit next to Arnie, Lulu is missing from that seat, then reappears in the next shot. (00:07:47 - 00:08:18)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: When Arnold and Lulu are in the swimming hole, Lulu tells Arnold to meet her later for a private swim. Then, when Arnold tells her, "But you're Arnie's girlfriend," his hat is missing. (00:05:14)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: In the country store, when Arnold says, "But, what about Arnie?" and it cuts to Arnie counting the bubble gum, the "1893" on the window is red but changes to white in the next shot. The "Est." also disappears. (00:05:53)
Arnold Visits Arnie / Chocolate Boy - S5-E12
Continuity mistake: Arnold Visits Arnie: When Arnold walks out of the movie theatre, he walks into Hilda and they fall over. In the next shot, they turn 90° counterclockwise. (00:06:45)
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.