The One With Barry & Mindy's Wedding - S2-E24
Continuity mistake: When Chandler is sitting in his kitchen with Monica and Phoebe, talking to the woman on his computer, the camera is on Monica, showing part of the computer screen. The screen is blank, indicating that the computer is off. In the next shot, the sound of an instant message is heard, indicating that the computer is in fact on. (00:13:10)
The One With Barry & Mindy's Wedding - S2-E24
Continuity mistake: When Rachel is worrying about how embarrassed she was, her hands move from her head to her hat with no time to move them. (00:11:20)
The One With Barry & Mindy's Wedding - S2-E24
Audio problem: When Rachel asks Barry and Mindy why people keep telling her to 'get well soon' and Barry says his parents told everyone she has syphilis, and in the next shot it shows Rachel trying to take this information in, Barry seems to still be talking, but no sound is coming out of his mouth. (00:09:25)
The One With Barry & Mindy's Wedding - S2-E24
Continuity mistake: Phoebe takes out her gum before kissing Joey. After she kisses him, she makes a comment about it and her mouth is empty. In the next shot, she sits down and is chewing. But she doesn't put the gum back in. (00:02:22)
The One With Barry & Mindy's Wedding - S2-E24
Revealing mistake: When Chandler finds out that his online girlfriend is married, the camera cuts to Joey, and you can see the computer screen is off.
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.