Time Machine - S1-E5
Corrected entry: Before Al uses the Time Machine for the first time, the clock/Time Machine reads 11:32. He then sets it to return thirty minutes into the past. However, when he finally returns to his cave, the clock reads 11:30, 32 minutes into the past.
Correction: The Time Machine is shown to be unreliable and prone to breakdowns. This is just another of its failings.