The One Where Chandler Takes a Bath - S8-E13
Continuity mistake: When Joey is talking to Chandler about London, Chandler's wedding ring keeps disappearing and reappearing. (00:03:10)
The One Where Chandler Takes a Bath - S8-E13
Continuity mistake: When Chandler is in the bath with Monica at the end a splodge of bubbles appears on his face between shots. (00:20:40)
The One Where Chandler Takes a Bath - S8-E13
Continuity mistake: When Chandler takes hold of the boat he grabs the middle of it, the camera changes angle and he is now holding it at the end of the boat. (00:06:20)
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.