The One With the Male Nanny - S9-E6
Visible crew/equipment: After Rachel and Ross hire the new nanny, when it cuts to Chandler walking into Joey's apartment, we can see the opening in the wall beside the door.
The One With the Male Nanny - S9-E6
Continuity mistake: When Mike and Phoebe are at Central Perk, Mike pulls his apartment key out of his pocket and he's holding the head of the key with the shank side up, but next shot he's holding the shank with the head side up.
The One With the Male Nanny - S9-E6
Continuity mistake: Towards the end, during a scene at Ross and Rachel's, Sandy picks up two puppets and puts them on each hand. He starts pulling the blue one onto his left hand, but when the angle changes there's a yellow one on his left hand, and a blue one on his right. It cuts to Ross, then when we go back to Sandy they've changed hands again. (00:24:30)
The One With the Male Nanny - S9-E6
Continuity mistake: When Phoebe is trying to explain to David that she really cares about Mike the door behind David is closed, but when Mike walks in that door is wide open, and it remains open until it's suddenly closed when Mike warns David that if he ever goes to Minsk he'd better watch out.
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.