Remy Rides Again/Hassle in the Castle - S5-E10
Revealing mistake: In the episode Hassle In The Castle, in the hall of Infamy the name plates are either scribbles or they're just blank.
Revealing mistake: When the school bus is shown cruising around the corner on the way to the camping area, you can see that as it turns the corner is is virtually empty. (01:38:50)
Revealing mistake: When Marco is telling Ellie about getting study candles, the power goes out, but behind them the electrical fan is still running.