The One With the Male Nanny - S9-E6
Visible crew/equipment: When Chandler says "pity laughs," all the stage lights are reflected in the pots behind him. (00:20:50)
The One With The Flashback - S3-E6
Continuity mistake: When Ross is talking to Phoebe and puts shot glasses on the bar, they're in groups. In the long shot, they're in a straight line then in a closer shot they're in groups again. (00:17:20)
The One With All The Thanksgivings - S5-E8
Visible crew/equipment: Monica is explaining her Thanksgiving to Chandler; when she drops the knife there is a shot looking up from the floor. A crew member's shadow is visible on the ceiling. (00:07:10)
The One With All The Kissing - S5-E2
Continuity mistake: There is a scene in Central Perk where Rachel confronts Chandler about all the kissing he's been doing. She raises her hands up in front of her and tells Chandler to hold on to stop him from getting up from the couch. As he goes to sit back down on the couch she lowers her hands to her lap. The shot cuts to an angle behind Rachel's chair and she is lowering her hands again. (00:14:35)
The One Where Monica and Richard Are Just Friends - S3-E13
Continuity mistake: Monica and Richard are squishing tomatoes; when she starts dabbing his shirt with club soda the door behind them leading to Monica's room goes from open to shut between two shots. (00:08:30)
The One With The Fertility Test - S9-E21
Continuity mistake: Just before we see Janice, Monica has her hands on Chandlers chest. When it cuts to the wide shot, her hands are round his neck. When Chandler says 'Aw come on.', her hands are on his chest again. (00:12:50)
The One with Two Parts: Part 1 - S1-E16
Continuity mistake: Just after Marcel switches the TV to "SAP," Joey comes back and tells Chandler about Ursula and how she gave him extra food. Chandler is holding a bottle of water, and before the camera cuts to Joey it is open, but when he is talking it is capped, and finally when Chandler says "Score," the bottle is open again. (00:07:05)
The One With The Donor - S9-E22
Continuity mistake: When Monica is asking Zack if he or any of his blood relatives has diabetes, Zack's cutlery changes position twice. In the shot facing him he has his fork in his left hand and his knife in his right. When it changes to a side shot, he is gesturing and doesn't have anything in his hands, without having time to put the cutlery down. Then when it cuts back to a front shot, he picks up his fork, which is now on his right, and starts eating. (00:14:30)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: When Joey and Angela talk in Central Perk, the black waitress with long hair is visible the background of shots of Angela. When we see shots of Joey the same waitress is also behind him near Gunther. She is in two places at once. (00:05:50)
The One With The Mugging - S9-E15
Continuity mistake: When Rachel is asking Joey what he's doing with all the liquid, her drink changes places depending on the shots. (00:14:50)
The One With The Engagement Picture - S7-E5
Continuity mistake: When 'Hums While He Pees' hands Phoebe the tickets for the ballroom dancing, they switch hands depending on the camera angle. She takes them in her right hand, but in the shot from behind she has them in her left hand. (00:08:25)
The One With The Dirty Girl - S4-E6
Continuity mistake: At the beginning of the episode where they are watching Ross through the window, Phoebe is leaning forward and standing to the left of the pole next to Chandler. When the shot changes to Ross coming through the door, she is suddenly standing up straight and is now behind Joey and Chandler. (00:00:10)
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 Where Rachel Tells... - S8-E3
Continuity mistake: In the scene after Rachel has told Ross, she finishes the magazine and tells him there is no pressure on him, his hand is on his chin, then almost instantly his hand is down. (00:11:20)
The One With Ross's Wedding, part 1 - S4-E23
Continuity mistake: Rachel is cutting flowers and she and Phoebe are discussing if she loves Ross. Phoebe's necklace switches sides every time the shot goes back to her. (00:07:35)
The One Where Rachel Smokes - S5-E18
Continuity mistake: Joey's snowcone changes during the scene with Ross at the party. It goes from rounded to more flat to rounded, and from plain ice to being able to see the flavoring to ice again. (00:20:00)
The One with All the Poker - S1-E18
Revealing mistake: When Rachel is doing the shuffling trick, it is clear that it is a trick deck. The cards, whilst flying from one hand to the other, change the angle of flight in mid-air, and some of them even move backwards as she moves her hands further apart from each other. This could only happen if the cards were connected to each other. (00:13:20)
The One With The Ballroom Dancing - S4-E4
Other mistake: Right at the end of the episode, Phoebe's got a job interview. We see the outside of a massage parlour, but the name on the awning has been superimposed - it moves about a bit while the shot itself is still. (00:20:45)
The One With The Boob Job - S9-E16
Continuity mistake: When Mike goes to leave Phoebe's apartment at the start, he puts his jacket over his arm twice. (00:02:10)
Audio problem: Right after Ross and Rachel leave the wedding chapel, Joey and Phoebe rush in. Joey is saying "C'mon, Pheebs, hurry, hurry." and she is saying "Okay, okay." However, neither one is moving their lips. (00:00:25)
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.