The One Where Rachel Tells... - S8-E3
Continuity mistake: In the scene where Monica and Chandler are trying to get in the first class lounge, Monica has a green bag on her left shoulder. It switches mid-scene to her right hand, and then appears back on her left shoulder. (00:08:40)
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.
The One With Rachel's Date - S8-E5
Continuity mistake: While Phoebe's in the kitchen with Monica and she's introduced to Tim the sous chef, the glass jar labeled "Monica's jar" suddenly appears on the shelf near the door, and it continues to vanish and reappear.
The One With Ross' Step Forward - S8-E11
Continuity mistake: It's obviously December, with the set decorations and Rachel's reference to sitting on multiple Santas' laps because she is randy from her pregnancy hormones. The characters establish that it's Rachel's fourth month of pregnancy...but she became pregnant about six weeks before Monica and Chandler's May 15 wedding. Her fourth month would have been in July, not December.
The One With The Rumor - S8-E9
Continuity mistake: When Will is demanding yams, it shows Ross looking towards the door; the camera then cuts to Will, and Ross is now looking at Will without time to move his head. (00:11:55)
The One With The Video Tape - S8-E4
Continuity mistake: When Chandler and Monica are trying to call Greg and Jennie, the water bottles on the table move around. Phoebe and Joey didn't move them, they are drinking from the cans. (00:05:30)
The One With The Video Tape - S8-E4
Continuity mistake: As Rachel goes to put the video on, Ross hangs his head. The camera cuts and now it isn't hanging. There was no time to move it between camera cut. (00:16:10)
The One With The Secret Closet - S8-E14
Continuity mistake: In the scene where Rachel comes in to have Joey feel her stomach, he gets up from the bed and you can see the boxer shorts he is wearing. You can also see them at the end of the scene, even though he is supposed to be naked. (00:03:00)
The One With The Stripper - S8-E8
Continuity mistake: When Phoebe is trying to place the stripper at the beginning, her coffee cup on the table keeps changing position. (00:00:50)
The One Where Chandler Takes a Bath - S8-E13
Continuity mistake: When Joey is talking to Chandler about London, Chandler's wedding ring keeps disappearing and reappearing. (00:03:10)
The One Where Rachel Tells... - S8-E3
Continuity mistake: When Joey and Phoebe are talking about the towel incident, Joeys arm goes from bent to straight depending on the angle. (00:03:40)
The One With The Birthing Video - S8-E15
Continuity mistake: When Chandler tells Monica and Rachel to look up and see the baby as it is being born, Monica takes her hands off her face twice and Rachel changes to the same position twice. (00:17:00)
Continuity mistake: When Monica says she wants to dance, her hair is always changing depending on the shot. (00:21:30)
The One With The Video Tape - S8-E4
Continuity mistake: When Chandler says about Ross and Rachel having a baby, He lifts his bottle to have a drink, camera changes and he raises it again. (00:02:25)
Continuity mistake: Near the end when Monica and Chandler are going on to dance for the last time, Monica speaks and her hair is neatly behind her right ear. The shot then looks to Chandler before going back to Monica immediately. However her hair is suddenly behind her left ear when she can't have moved it as her hands are in the shot at all times. (00:21:15)
The One With Rachel's Date - S8-E5
Continuity mistake: When Ross says goodbye to Rachel near the end, she lowers the bag of sweets to her waist. Then in a close up of her looking thoughtful it's up by her chest. (00:20:10)
The One With Ross' Step Forward - S8-E11
Continuity mistake: In the scene when Phoebe comes in to tell Rachel she is sorry about the whole thing with Roger, Rachel is eating ice cream, and sets it on the counter and in the next shot sets it down again. (00:23:25)
The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: While Rachel is having her baby she grabs Ross by the shirt and says 'you do it for me' in the next shot her hand is no-where near Ross. She couldn't have put her arm down that quickly. (00:33:50)
The One With The Video Tape - S8-E4
Continuity mistake: As Rachel says, "Let's be honest" to Ross, her hands are in her lap. The camera cuts and now she is gesturing with them. (00:03:30)
The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: When Phoebe and Ross are standing in front of the screen looking at all the babies and talking about why He and Rachel aren't together, some of Phoebe's hair is in front of her shoulder on the right hand side then the shot changes looking over Phoebe's shoulder at Ross. Then when you see Phoebe again her hair is behind her shoulder yet she has not moved or touched her hair. (00:45:00)
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.