Visible crew/equipment: During the scene when Phoebe breaks into the other Phoebe's house and gets caught, the older Phoebe was telling the younger one that the man in the photo is not Frank Buffay, but is Chuck Mangioni. Right after that, as Phoebe 2 walks towards the camera, you can see that the door behind her moves open, and there is a visible shadow of someone who walks by that doorway. (00:19:00)
Friends (1994)
Episode list - season 9
Starring: Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matthew Perry, David Schwimmer, Matt LeBlanc
More mistakes in Friends
The One With Chandler In A Box - S4-E8
Monica: Fine, judge all you want to, but [to Ross] married a lesbian, [to Rachel] left a man at the altar, [to Phoebe] fell in love with a gay ice dancer, [to Joey] threw a girl's wooden leg in a fire, [to Chandler] LIVING IN A BOX!
Trivia: Matthew Perry's wit is so legendary that the scriptwriters have often incorporated his gags into the show.
The One With The Dirty Girl - S4-E6
Question: When Joey asks why he can't give Kathy the pen, Chandler says, "Because she's not eleven. And it's not the seventh night of Chanukah." What is Chandler talking about when he says, "It's not the seventh night of Chanukah?"
Answer: Chanukah is a Jewish celebration that occurs around the same time as the Christian Christmas. The celebration lasts for eight days and it is customary to give a small gift on each of the eight days. There is no special gift required and the line about it being "the seventh night" of Chanukah is just Chandler's sarcasm.
Answer: Usually by the seventh night of Hanukkah you don't know what to get the other person, and you will probably resort to getting the other person something insignificant. Chandler is basically saying that the pen is a stupid gift.