The One Where Joey Tells Rachel - S8-E16
Continuity mistake: At the end of the previous episode, Joey tells Ross that he has feelings for Rachel just as Ross is about to walk out of Central Perk, and there's a vase of tulips on the table beside the door and two things hanging on the coat hooks. The opening scene of this episode continues at the same moment of Joey's admission, and the vase has vanished and there's only a sweater hanging on the coat hooks.
The One Where Joey Tells Rachel - S8-E16
Continuity mistake: When Monica and Chandler get back to the apartment Chandler tosses his coat over the back of the couch, and while they're talking about soulmates and a house of cheese we can see Chandler's coat in the reflection on the TV, but then it vanishes in the reflection, though it reappears when Chandler says that he wants to take Monica out to a restaurant.
The One Where Joey Tells Rachel - S8-E16
Continuity mistake: When Monica is talking to Ross about how Joey feels, there is a shot of Monica bending down to talk to Ross, and some magazines on a table. At the end of the scene the magazines have changed place. (00:05:30)
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.