Continuity mistake: Near the end when Monica and Chandler are going on to dance for the last time, Monica speaks and her hair is neatly behind her right ear. The shot then looks to Chandler before going back to Monica immediately. However her hair is suddenly behind her left ear when she can't have moved it as her hands are in the shot at all times.
Continuity mistake: Towards the end of the episode, when Chandler comes into the apartment to talk to Joey about his kiss with Kathy, Joey turns the TV off and places the remote on the counter. However, the TV is suddenly back on after Joey asks, "Is that why you bought all this stuff?" (referring to the furniture}, and then Joey turns it off again manually.
Continuity mistake: When Rachel finds out that Ross and Julie are getting a cat, watch Rachel's tray. When she says "together?" she's got a towel that is flat; cut to Ross and Julie for a fraction of a second, then when it cuts back to Rachel saying "both of you?" it's now in a pyramid.
Continuity mistake: At the beginning when Rachel falls and starts bleeding, you can see that the wound is somewhere up above her forehead because the blood is running from the wound up there. However, throughout the rest of the episode she has a bandaid going horizontally across her forehead, nowhere near where the apparent wound was.
Continuity mistake: Monica and Chandler are in their apartment talking about Monica's worries that Chandler would dump her if she put on weight. When we first see Monica, the bite mark in her apple is quite small, but a few seconds later, it is suddenly much bigger without her eating any more of it.