Continuity mistake: Ross has always said that Carol was his first (and only, until Julie) sexual partner, but in the episode where they tell each others secrets Chandler says Ross slept with the cleaner when they were at college. Some people say that Ross had kept it a secret, and that's why it had never come out before, but considering that he categorically states several times over series one and two how he'd only EVER been with Carol, getting quite upset at times, that explanation just doesn't ring true.
Continuity mistake: When Rachel and Chandler are out in the hall eating cheesecake off the floor, Chandler's piece is much closer to Rachel's piece than in the previous scene when Rachel slapped it out of Chandler's hand closer to the apartment doorway.luke f
Continuity mistake: In the scene when Phoebe says goodbye to David, you can see Phoebe's long hair on her back. The scene goes back and forth between Phoebe and David or Phoebe and Joey (after David leaves). Each time the amount of hair on Phoebe's back changes. Sometimes it is a thin bit of hair, other times a large chunk (while the rest of her hair is framing her face in front). (00:19:10)