The One With Ross's Teeth - S6-E8
Visible crew/equipment: When Joey's in the kitchen holding a football waiting for Janine to come home, so he can talk to her about getting rid of the girly stuff, just as Janine walks into the apartment the camera can be seen at the right side of the screen.
The One With Ross's Teeth - S6-E8
Continuity mistake: In the opening coffee house scene Ross is holding a red folder, then it disappears and then he has it again. (00:02:05)
The One With Ross's Teeth - S6-E8
Revealing mistake: When Ross's date turns the lights down he can speak and yet the whiteness of his teeth doesn't show. (00:17:25)
The One With Ross's Teeth - S6-E8
Character mistake: While on his date with Hillary, Ross says that he has a five year old son. Ben was born in 1995 and this episode is set in 1999, so Ben should be four, not five.
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.