The One With Chandler In A Box - S4-E8
Continuity mistake: In the scene were Phoebe is calling for Monica's eye doctor, in the background you can see the TV is off. Then Phoebe asks if she wants to see the on call doctor, Monica says yes, and in the background the TV is on. (00:03:55)
The One With Chandler In A Box - S4-E8
Continuity mistake: In the episode with Chandler in a box, when Rachel is showing Ross all the things she had kept from their relationship in a shoe box, her hair is tucked behind her ear in most shots, but when she says "I keep the gifts that matter", it's all loose, then goes back to how it was in the following shot. Also in the shot before that line she's pointing the horn fossil's tip at Ross, but when it cuts to a front view she's holding the horn's tip and pointing the broken end. (00:16:30)
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.