Other mistake: When Joey announces that he has a job in the new Al Pacino movie, Ross is holding a bottle of peach Snapple with part of its brand name whited out, so it reads "S pple" on the label. (00:13:50)
The One Where the Monkey Gets Away - S1-E19
Continuity mistake: When Rachel tells Ross that she "kind of lost" Marcel it cuts to an exterior shot from the balcony, and if we look past Rachel and Ross we see there's a table against the wall, under the Maïna La Voyante poster, but that table does not exist in previous or following shots. (00:10:15)
The One with All the Poker - S1-E18
Other mistake: During the third game of poker, the bottle of raspberry Snapple on the table has part of its brand name whited out on the label.
The One with the Fake Monica - S1-E21
Visible crew/equipment: After Marcel has humped the chair, when it cuts to Joey walking in saying that there already is a Joseph Stalin, we can see the reflection of a crew member (presumably female) in the small mirror on the wall who's wearing a black top-and it's not Rachel, the angle is off.
The One with the Boobies - S1-E13
Continuity mistake: When Joey's mom comes to tell him that she knows about the affair, he places the paper bag that she brings on the stove and it falls over. In later shots, it is obvious that the bag is upright. (00:17:05)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: The positions of the mugs shift between shots.
The One Where Monica Gets a Roommate - S1-E1
Other mistake: At the end when Ross and Rachel split an Oreo, you can see that Rachel is holding 2 parts and Ross somehow still has one. (00:20:38)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: When the horrible woman says "no suds, no saves", Rachel's hands suddenly appear on her basket. (00:11:30)
The One with the Candy Hearts - S1-E14
Visible crew/equipment: Just as Joey and his date are leaving, a stage light and the top of the set drop into view above Chandler. (00:08:10)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: Phoebe says she's going to break up with Tony, and Monica has her cheque book in her hand pointing away from her lap. Camera cuts and now it's in her lap. (00:03:00)
The One with the Dozen Lasagnas - S1-E12
Audio problem: The very last line of the episode (Monica saying "and I'm gone") is an overlay. (00:22:40)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: At the start, Chandler and Joey have their hands outstretched. Camera cuts and now Chandler's hand is lowered. (00:00:50)
The One with George Stephanopoulos - S1-E4
Continuity mistake: Monica asks Phoebe if she has a plan to which she replies she doesn't even have a "Pla." During this, her hairs position on the futon changes between shots. (00:14:40)
The One with George Stephanopoulos - S1-E4
Continuity mistake: The facial expression of the receptionist changes drastically between instant cuts when she says the line "any minute now" (00:14:00)
The One with George Stephanopoulos - S1-E4
Continuity mistake: The way the receptionist in the hospital holds the candy bar differs between the several camera angles. (00:13:30)
The One with George Stephanopoulos - S1-E4
Continuity mistake: When Ross gets hit with the puck, we see it flying towards him. Camera cuts and the puck has simply vanished and yet Ross acts as though he has been hit. (00:12:45)
The One with the East German Laundry Detergent - S1-E5
Visible crew/equipment: When the horrible woman enters, a tape marker is visible on the floor by the machines. (00:11:20)
The One with the Thumb - S1-E3
Audio problem: When Monica is first seen in the kitchen complaining about taking a guy home, the other chef is cutting some items up. However, the audio of the knife clicking as it hits the board is overdubbed. (00:08:00)
The One Where Monica Gets a Roommate - S1-E1
Visible crew/equipment: We get a close-up of the coffee pot when Rachel asks if anyone would like some. In this shot, there are 3 stage lights reflected clear as day. (00:27:50)
The One Where Monica Gets a Roommate - S1-E1
Continuity mistake: Near the end when Phoebe says to Monica, "C'mon give me your feet" she puts the red pen down on the blue paper. When Monica sits down though, the red pen is on the table and not the blue paper. (00:23:40)
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.