The One With The Dirty Girl - S4-E6
Visible crew/equipment: When Monica leaves the kitchen into the next scene, the boom mic is visible at the top of the screen above the kitchen door for a short period of time. (00:07:40)
The One Where Nana Dies Twice - S1-E8
Continuity mistake: Just before the group of guys at the funeral shout about the football, there is a glass of wine next to Monica's mother which is about 1/3 full. After a brief cut away, the next shot shows the glass is almost empty. (00:19:05)
The One With The Birthing Video - S8-E15
Continuity mistake: In the one where Chandler watches the video of a woman giving birth, he takes a video out of the VCR and places it on the table (he's staring at the box and when Monica moves it we hear that a tape's inside). When Monica enters the room, she asks him what he is so upset about and he presses play on the remote control. The tape immediately starts playing, despite no-one moving to put it in the player. (00:06:30)
The One Where Chandler Doesn't Like Dogs - S7-E8
Deliberate mistake: When Phoebe is trying to sneak the dog out of the apartment, the guys say that they have noticed that the bag is moving, yet the bag doesn't move at all. (00:04:10)
The One With The 'Cuffs - S4-E3
Continuity mistake: In Joanna's office, Chandler and Rachel are pulling his pants from one another while he is cuffed to the filing cabinet. Right before Rachel says "What if I clean your bathroom for a month?" she throws the pants onto a chair, but then when Chandler later says "Freedom. I want my freedom. Why won't you hear me?" he opens the door to yell to Sophie and they are both holding the pants again. (00:15:10)
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 Phoebe's Uterus - S4-E11
Continuity mistake: At the beginning, Alice and Frank tell Phoebe that they have been trying to get pregnant. When Alice says, "You know, no one's getting any younger", Frank looks at Alice and laughs. In the next shot however, he is looking at Phoebe and doesn't seem to laugh. (00:01:00)
The One with the Stoned Guy - S1-E15
Continuity mistake: At the end of the episode when everyone is comforting Monica, Ross has his hand on her shoulder. In the next shot it is above his knee as he stands up. (00:20:05)
The One With All The Candy - S7-E9
Continuity mistake: When Phoebe tries to show the gang she can ride her bike, the large metal bike rack at the curb changes position between shots. (00:09:50)
Plot hole: In TOW Ross tells Rachel he cannot see her following a promise to Emily, the rest of the friends go into Monica's bedroom. Joey hauls out a box from under the bed, saying that he's been hiding it there since Ross said the wrong name at the wedding. Surely Monica, with her obsession for keeping the place clean, would have noticed a box under her bed? (00:04:10)
The One With The Lesbian Wedding - S2-E11
Audio problem: During the lesbian wedding, whenever we see a shot of Carol and Susan while the minister is talking, her mouth is not moving. (00:18:35)
The One with the Dozen Lasagnas - S1-E12
Continuity mistake: When Paulo is about to get his massage, he puts his hand on his hip. In the next shot, he is leaning forwards and both hands are out strecthed in front of him. (00:09:00)
The One With The Ride-Along - S5-E20
Continuity mistake: Toward the end of the episode, Rachel is back in Ross' apartment, trying to mend the ornament she broke when she was in there earlier. Ross comes in unexpectedly and she tosses the broken pieces into the lightshade, leaving the glue on the side table. In subsequent shots, the glue goes from lying on its side, to standing up, a number of times. (00:16:00)
The One With The Proposal, part 1 - S6-E24
Continuity mistake: When they are in Central Perk deciding who will go with Rachel to the auction, Rachel's purse and the cups in front of Joey move around. (00:02:20)
The One With Ross's Grant - S10-E6
Continuity mistake: When Charlie and Benjamin are at the restaurant, Benjamin says "I can't believe you chose this restaurant. You remember that night?" To which Charlie replies "I can't believe they let us back in here." However in "The One With The Fertility Test" Charlie has never been to New York before.
The One With The Triplets - S5-E3
Revealing mistake: When the doctor says, "Here comes the head," it is very obvious that there are feet coming out. (00:14:50)
The One With The Proposal, part 1 - S6-E24
Factual error: There's no charity event in the world that would be clamoring for non-paying guests and offering them free food and an open bar.
The One Where Rachel Quits - S3-E10
Continuity mistake: In the very first shot of Chandler and Rachel sitting on the couch, Chandler has his legs crossed left over right, but it cuts to the closeup and his legs are crossed right over left, then it's back to left over right.
The One The Morning After - S3-E16
Continuity mistake: When Ross is listening to Rachel's message on his answering machine, only the open pill bottle sits on the counter beside his mug, but then the bottle cap and cotton filler suddenly appear next to it. (00:03:00)
The One The Morning After - S3-E16
Continuity mistake: While Monica's preparing her shake in the blender she asks Rachel about the anniversary dinner, and when Rachel tells her that she and Ross broke up, Monica throws the blender lid and it flies over the counter, but in the next shot the lid is back in Monica's hand, and then it vanishes again. (00:01:10)
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.