The One With Rachel's Dream - S9-E19
Continuity mistake: In the scene where Ross and Chandler are checking into the hotel, the box of maple candy Ross is holding keeps switching from the front of the box facing us to the back facing us. (00:07:20)
The One With the Sharks - S9-E4
Continuity mistake: When Chandler and Monica are talking about Chandler's shark obsession, his arms keep changing with each shot. When the shot is from behind (facing Monica) they are on the couch, and when the shot is in front (facing Chandler), his arms are folded in front of him. (00:19:35)
The One Where No One Proposes - S9-E1
Revealing mistake: When Rachel is breastfeeding Emma for the first time, the baby's head is constantly moving in the same repetitive pattern suggesting it is one of those life-like dolls. Babies do not move their heads like that. (00:08:20)
The One With The Mugging - S9-E15
Continuity mistake: When Chandler, Rachel and Monica are discussing the sneakers, Rachel is holding a water bottle. In a close up shot it has the cap on it, in the next far shot it is on the table without a cap. (00:15:30)
The One With The Fertility Test - S9-E21
Continuity mistake: When Charlie tells Ross about the Met, Ross goes sitting next to her, and his hands are empty when he says: 'Joey really knows his art, huh?' When Charlie says: 'Not so much' Ross suddenly holds a book in his hands. Then, when the shot changes, the book is gone again. It keeps (dis)appearing during the scene. (00:20:35)
The One With Christmas in Tulsa - S9-E10
Continuity mistake: When the group notice that it's snowing outside, external shots show a lot more snow than the internal shots. (00:19:20)
The One Where Emma Cries - S9-E2
Continuity mistake: When Joey is seen apologising in front of the hospital room door, we can see a pink wall only about 2 metres behind him. However, in every scene before that which features the door, we can see it leads out to a large open area.
The One With The Fertility Test - S9-E21
Visible crew/equipment: After Chandler tells Monica the results of the fertility tests, when it cuts to Phoebe as the receptionist says good morning to her, the camera can be seen at the left side of the screen.
The One With Ross's Inappropriate Song - S9-E7
Other mistake: When Joey and Chandler are watching Richard's sex tape the screen is off right before Monica comes in, and yet she sees the video playing (you can still hear sex noises with the screen off). (00:14:40)
The One With Christmas in Tulsa - S9-E10
Audio problem: In the scene before the opening credits, if you listen carefully to Chandler's line, "If I don't get it done, I'll be fired", you can tell it's an overdub. The background noise and volume levels are different than the rest of his speaking. (00:00:33)
The One In Barbados, part 1 - S9-E23
Plot hole: This is actually for both parts of "The One in Barbados": it's shown that Monica's hair gets all frizzy from the humidity. And yet she's shown all throughout with her hair out and loose in all its frizzy glory, though it bugs her. I could maybe buy that not one of the women have hair gel with her (not bloody likely.) or that the fancy hotel doesn't sell hair gel (possible). But resourceful Monica would have thought of something to calm down her hair, or she would have just tied it up in a ponytail or bun - she does care a lot about her appearance. It makes no sense other than for comic value. (00:09:30)
The One With The Blind Dates - S9-E14
Visible crew/equipment: When Phoebe meets Joey to tell him about the date for Rach, the stage lights are seen outside the coffee-shop. (00:05:35)
The One With The Blind Dates - S9-E14
Continuity mistake: When Rachel is at her blind date, and Steve tells her that he's selling T-Shirts now, Rachel's arms are on the table, but then the camera cuts to her, and she has her arms crossed. (00:12:00)
The One With Rachel's Other Sister - S9-E8
Character mistake: While watching the parade near the beginning, Chandler gets excited because there's a band from Muskogee, OK, which is supposedly only four hours from Tulsa, where he works. It's actually less than an hour away from Tulsa.
The One With the Pediatrician - S9-E3
Continuity mistake: In the scene where Phoebe asks Mike to prove that he plays piano, his arm goes from resting on the couch to on his lap from one shot to the next. After Phoebe tells him "You are really good," his left arm is resting on the couch. But in the next shot when Phoebe continues talking, his arm is resting on his lap.
The One With The Lottery - S9-E18
Continuity mistake: After he gets the job Chandler sits on the couch pretending to read a magazine and Joey drops a piece of paper that materialises in his right hand in between shots. (00:19:40)
The One With the Male Nanny - S9-E6
Continuity mistake: When Phoebe is trying to explain to David that she really cares about Mike the door behind David is closed, but when Mike walks in that door is wide open, and it remains open until it's suddenly closed when Mike warns David that if he ever goes to Minsk he'd better watch out.
The One With Rachel's Other Sister - S9-E8
Continuity mistake: When Chandler puts the box of china down on the chair, the lid of the box is shut, but a bit later the box is wide open.
The One With The Mugging - S9-E15
Visible crew/equipment: When Chandler slips while wearing the shoes, if you look above Monica and Rachel, you will see a stage light.
The One With Ross's Inappropriate Song - S9-E7
Audio problem: When Emma laughs right before Ross comes in, the laughs don't match with her lips.
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.