The One Where Joey Dates Rachel - S8-E12
Continuity mistake: When Ross arrives at the classroom late and out of breath, he tosses his jacket at the hook, but it falls to the floor, and he walks behind the desk anyway. In the next wideshot of the class, as Ross still stands behind the desk, the coat is up on the hook. (Viewed on broadcast TV as a rerun, so there may be a missing shot that was removed for extra commercial time.). (00:07:05)
The One Where Joey Dates Rachel - S8-E12
Continuity mistake: After Chandler has been playing the Ms Pacman machine all day he claims his hand has seized up and it appears to look like a claw. From then on in that scene, his hand manages to move around fine. It goes in his pocket, and he waves it around like normal, and then when he mentions his hand again at the end of the scene, it appears to have seized and is clawlike again. (00:10:30)
The One Where Joey Dates Rachel - S8-E12
Continuity mistake: When Phoebe is playing Ms. Pacman to erase Chandler's high scores, the door of the apartment can be seen open. When she loses and starts swearing, Ross enters the apartment with Ben, opening the door. (00:19:10)
The One Where Joey Dates Rachel - S8-E12
Continuity mistake: At the end Ross rips the map but in the next shot it's repaired. (00:21:00)
The One Where Joey Dates Rachel - S8-E12
Continuity mistake: When Phoebe flips out after losing the game and starts her cursing rant, Ross and Ben came in by opening the front door, but in all of Phoebe's closeups the front door is closed behind her.
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.