The One With the Baby on the Bus - S2-E6
Continuity mistake: In the scene where Chandler and Joey want to meet women with Ben, Chandler is holding the baby. A little after Chandler says, "Oh seriously you want him?" The position of Chandler's hands holding Ben changes between shots. (00:05:55)
The One With the Baby on the Bus - S2-E6
Continuity mistake: When Stephanie is singing "Angel in the Morning", there is a person in overalls sitting behind the green pole. The shot changes to Phoebe outside and you can still see the person; it changes back to Stephanie and the person is now sitting on the next table. (00:16:00)
The One With Ross' New Girlfriend - S2-E1
Deliberate mistake: The door to Monica's bedroom is open in many shots, such as when Ross introduces Julie, and we can see that there's a wall (with a framed picture) directly opposite the doorway, but when Phoebe's giving Monica the haircut they're in Monica's bedroom and there's no such wall in front of the door.
The One With Two Parties - S2-E22
Continuity mistake: When Chandler and Joey are in Monica's apartment blowing up balloons, Chandler's balloon changes type. The camera changes and it goes from shiny to dull. (00:03:30)
The One Where Joey Moves Out - S2-E16
Revealing mistake: When Chandler and Joey are arguing, they go into their rooms and slam the doors. By Chandler's door, you can see the wall move. (00:10:35)
The One With Ross' New Girlfriend - S2-E1
Continuity mistake: When Paulo comes out of Rachel's bedroom to greet the group, the robe he is wearing is obviously untied and hanging open. After we see how everyone reacted to him being there, we again see Paulo but now the robe is securely tied even though neither he nor Rachel changed positions between shots. (00:11:10)
The One With Phoebe's Dad - S2-E9
Continuity mistake: In the scene where Monica and Ross walk in carrying a few carrier bags, Monica takes out a pack of green plates, but in the next shot she is holding 4 packs of plates - 2 green, 2 red. She did not have time to pick up another pack between shots. (00:08:05)
The One Where Joey Moves Out - S2-E16
Visible crew/equipment: When Monica, Richard, and Ross arrive at the party, the boom mike is seen at the top of the screen. (00:03:50)
Continuity mistake: When Monica goes to the mockolate interview, at one point she says "abso...lutely." While she is saying this, the mockolate packet is in her hands, but when the shot changes, the packet is on the table. (00:06:10)
The One Where Ross Finds Out - S2-E7
Continuity mistake: When Rachel finds out that Ross and Julie are getting a cat, watch Rachel's tray. When she says "together?" she's got a towel that is flat; cut to Ross and Julie for a fraction of a second, then when it cuts back to Rachel saying "both of you?" it's now in a pyramid. (00:05:15)
The One With Ross' New Girlfriend - S2-E1
Continuity mistake: At the very beginning of the episode, the blood on Rachel's head changes a few times throughout that opening scene. (00:01:15)
The One After the Superbowl, part 1 - S2-E12
Continuity mistake: When 'Drake' is having dinner with Erica (the stalker), Joey is seen to be wearing a ring on the ring finger of his left hand. This can been seen just before another diner begins to choke. When the episode cuts back to them in the restaurant, the ring is gone. (00:09:50)
The One With Phoebe's Dad - S2-E9
Continuity mistake: Phoebe says to Chandler that there is no seatbelt as the paramedics had to cut it. but a few seconds later, you can see a seatbelt. (00:12:25)
The One With the Baby on the Bus - S2-E6
Factual error: In the one where Joey and Chandler lose baby Ben on a transit city bus, they later have to pick him up at the transit city headquarters. The man working there assumes that one of them is the father. There is no way that a city official would just give away a baby without checking for ID or a birth certificate or proof of fathership of the child. (00:14:30)
The One With The Chicken Pox - S2-E23
Continuity mistake: When Monica says about Richard not having a 'thing', her arms change place depending on the shot. (00:14:10)
The One With the Breast Milk - S2-E2
Continuity mistake: When Ross thanks Monica for going shopping with his new girlfriend, Monica has her arm up, and the camera cuts, the arm is down with no time to do so. (00:04:00)
The One With Phoebe's Dad - S2-E9
Continuity mistake: In the scene when Joey is asking Ross to show him the presents he bought, Joey uncrosses his legs twice. (00:03:20)
The One After the Superbowl, part 1 - S2-E12
Continuity mistake: When Phoebe gets the kids to sing along to 'That's another thing that you don't wanna do', there is a little boy and girl sitting perfectly still. The shot cuts to a close-up, and one of them is now standing and they are both swaying. (00:11:40)
The One After the Superbowl, part 2 - S2-E13
Continuity mistake: When Susie is asking Chandler to wear her undies, her hand is on his neck. In the next shot it is gone, and then it is back again. (00:08:45)
The One With the Breast Milk - S2-E2
Other mistake: After the opening credits, the clip of cars driving at night in New York is played backwards. (00:02:39)
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.