Continuity mistake: Rachel and Phoebe are in the Central Perk, talking about leaving the group, and a jacket and a handbag are hanging on the arm of the chair behind Rachel, slightly to her left. Between shots it changes from just the jacket, then just the handbag and so on. This continues throughout the scene when Ross comes in and Phoebe leaves. As she gets up you see both again, however Rachel does not move enough to just show one and hide the other.
Continuity mistake: When the group is in the coffee house discussing Kip there is a bag on the table in front of Monica. When Rachel enters she places her bag on top of the bag already sitting there. Toward the end of this scene Rachel's bag then disappears and only the original bag is now sitting there.