Baby Shower - S2-E15
Continuity mistake: At the beginning of the show, Peter is scraping the ice off his windshield, but the scraped pattern we see from inside the car is different from the pattern outside. When the car won't start, he gets out, and more of the windshield has been scraped in the meantime.
Answer: It was in "Chaos Theory", the first episode of season 9 (time code 00:13:55).
Super Grover ★