The One With The Engagement Picture - S7-E5
Corrected entry: During the scene where Rachel gets Tag's scarf out of his backpack and smells it, a coworker walks up. Rachel puts on the backpack to disguise what she was doing. The camera cuts away a few times and the final time she does not have the backpack on anymore.
Correction: If you watch carefully you see it all the time. Since she is wearing a black coat it's sometimes difficult to see, but the backpack is there and in the last scene she takes it off.
Anastasios Anastasatos