The Banker - S6-E13
Corrected entry: After The Banker asks Toby if there is any inappropriate behavior, a few seconds later there is a flash back of Season 3 Ep. 22 when it is the Beach Games and Michael is hosting a hot-dog eating contest. Michael says to Phyllis to "Dip it in the water so it'll slide down - your gullet more easily." In the flashback version, everyone says "That's what she said." In the real version, no one says anything. Not to mention Toby wasn't actually at the beach day, Michael told Toby to stay because "Someone needs to stay at the office."
Correction: Everyone in the real version does say that's what she said.
Remember the office is supposed to be a real TV show. So the show can add unseen footage from scenes to other episodes and it's normal and completely fine. I thought it was weird at first too but then I thought about the fact that it's supposed to be a real show.