The One With The Red Sweater - S8-E2
Continuity mistake: Monica is sitting in the living room with all her wedding presents, waiting for Chandler to return. She begins to open a large parcel and reveals a brown cardboard box. Then the camera moves to Joey, and when it moves back, the parcel is wrapped up again. This happens about three times. (00:05:05)
The One With The Apothecary Table - S6-E11
Visible crew/equipment: After Janine tells Joey that she'll apologize to Monica, in the shot of Janine walking into the hallway the end of the hall's set wall can be seen at the left side of the screen, and the corner of the camera can be seen moving at the right side of the screen.
The One With Joey's New Brain - S7-E15
Character mistake: After Susan Sarandon slaps Joey the first time, after he tells her that her character is dying on DOOL, she turns away and right before she is off camera she smiles, instead of maintaining her anger. (00:06:05)
The One With the Sharks - S9-E4
Revealing mistake: While Monica and Rachel are talking about Chandler's "jollies to Jaws" Rachel's wearing a colorful flowery top, and after Joey walks in just as Monica takes her seat at the table in the closeup, it's Jennifer Aniston's stand-in, wearing a blue top, who is seated beside Monica. Rachel's hair is wavy in the flowered top, but straight in the blue top (viewed in widescreen). (00:12:22)
Revealing mistake: In the episode where Joey is doubling Al Pacino's butt you can clearly see his shadow when he's shooting the scene in the shower, and he's wearing boxer shorts. (00:13:20)
Continuity mistake: The number of the flats near the start of the first series was 4 and 5. After a few shows they changed to 19 and 20. [The producers realised that the numbers 4 and 5 were for apartments on the lower floors and had shown Monica's apartment to be much higher up so they changed the numbers - it's still a mistake but there's the reason.]
Continuity mistake: Across Series 3 - 5, Ross remains the same age (29) for all three years. In Series 3 he tells Chandler, "No thanks, I'm 29" when offered chocolate milk; in Series 4 when the guys try to party without Gandalf they all say they're 29; and in Series 5 when he's trying to reconcile with Emily, he says either he does, or he would get divorced for the second time before age 30.
The One With Chandler's Dad - S7-E22
Revealing mistake: In the shot of the highway with Ross and Rachel in the Porsche before the police officer walks to them, it is very obvious that the people inside the car are not actually them.
The One With Phoebe's Ex-Partner - S3-E14
Visible crew/equipment: When Phoebe and Leslie finish singing the song Sticky Shoes, as they're hugging each other in the side shot, the second camera can be seen at the left side of the screen. (00:13:00)
The One With Phoebe's Ex-Partner - S3-E14
Visible crew/equipment: After Ross finds out that Mark quit his job, when Rachel and Ross leave the office, the second camera can be seen as the shot pans to the right, at the right side of the screen. (00:06:15)
The One with George Stephanopoulos - S1-E4
Visible crew/equipment: When the guy delivers the wrong pizza, in the shot after Monica grabs the pizza box to hand to Phoebe and shouts that they have George's pizza, the tape marks can be seen on the floor with one of them between the delivery guy's feet.
The One With The Worst Best Man Ever - S4-E22
Visible crew/equipment: While Joey, Ross, and Chandler are waiting at the vet's office, in the following flashback scenes with the duck, when Joey bathes the duck the end of the bathroom set wall can be seen at the right; and when Chandler's sitting in the canoe with the duck in the pail, a crewmember can be seen where the set wall ends. (00:19:45)
The One With Chandler In A Box - S4-E8
Visible crew/equipment: After Kathy tells Chandler goodbye and leaves Joey lifts the lid from the box, and when Chandler stands up in the box we can see the end of the living room set wall and the pink set wall.
The One With The Ring - S6-E23
Visible crew/equipment: In the opening shot of Phoebe and Chandler in the "nine millionth" jewelry store looking for a ring, at the top of the screen we can see the tip of the boom mic moving in the wideshot. Then just as Chandler looks into the display case and says, "Ugly ring. Ugly ring. Ugly ring," the boom microphone can be seen moving around in the mirror's reflection behind him.
The One With The Joke - S6-E12
Visible crew/equipment: When Joey announces that Central Perk will be closed for an hour he shows everyone to the door, and in the wideshot of people walking out the door we can see the camera turning at the top right side of the screen, just before the shot cuts away.
The One With The Princess Leia Fantasy - S3-E1
Visible crew/equipment: After Phoebe's Princess Leia impersonation in front of Ross it cuts to Joey watching Wheel of Fortune, and in the next shot as Chandler walks in the camera can be seen at the right side of the screen.
The One With Chandler's Work Laugh - S5-E12
Visible crew/equipment: After Joey and Phoebe place their betting cash on the counter, when Joey says, "Let's get the contestants out of their isolation booths," the end of the set wall can be seen behind the foosball table. (Widescreen version).
The One With Rachel's Date - S8-E5
Visible crew/equipment: While Phoebe and Tim are at Central Perk, when Tim's beeper goes off he blows Phoebe a kiss when he leaves, and as Phoebe catches that kiss and throws it away have a look at the left side of the screen, where the Central Perk wall ends we can see part of Monica's restaurant kitchen set - the door and the wall beside it. (Widescreen version).
The One Where Rachel Tells... - S8-E3
Continuity mistake: While Joey's on the phone with Monica telling her the phony story that he and Phoebe smell gas coming from her apartment, on the table are the glass casserole dish and lid from the chicken parmigiana and a water bottle, but in the closeup there's only a ceramic blue bowl filled with eggplants and squash, and it keeps switching in the following shots,.
The One Where the Monkey Gets Away - S1-E19
Continuity mistake: While Rachel's babysitting Marcel she's watching the soap opera on TV, and when she points out Dr. Francis there's a closeup of the TV and when she points out Raven there's another closeup, but the TVs in both closeups are different, as well as the items that are near the TVs.
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.