The One with Two Parts: Part 1 - S1-E16
Visible crew/equipment: When Rachel is taking the Christmas lights down, a boom mic is visible as the camera pans down when we first see her. (00:21:15)
The One with the Thumb - S1-E3
Continuity mistake: When Joey comes into Monica and Rachel's apartment and sits down, he puts his towel on his lap. In the next shot it is over his shoulders, then back on his lap again. (00:18:30)
The One with the Blackout - S1-E7
Continuity mistake: At the end of the episode, as Chandler turns to the security camera, he is stood right next to the door. In the next shot he has jumped about 2 feet away from the door instantly. (00:21:20)
The One Where Monica Gets a Roommate - S1-E1
Continuity mistake: During Monica's date, she points her fingers and asks, "What were you going to say?" In the next shot she is gesturing with her hand. (00:16:00)
The One with All the Poker - S1-E18
Continuity mistake: When the group is sitting around the table in Monica's apartment playing poker, Monica is making something to eat. When she puts it on the table and sits back, we can see a pile of plates on the table on her right side. But in the next shot, the plates are gone. (00:05:35)
The One Where Underdog Gets Away - S1-E9
Visible crew/equipment: When Monica shuts the TV off while watching skiing, there is a closeup of the screen as it goes blank. You can see reflected in the blank screen an image of a man in a long sleeved shirt and tie, who does not correspond to any of the characters in the room. (00:08:00)
The One Where the Monkey Gets Away - S1-E19
Continuity mistake: When Monica looks at Barry and Mindy's engagement notice in the magazine, she folds the page over. In the next shot, the magazine is open in her hands. (00:01:50)
The One with Two Parts: Part 1 - S1-E16
Visible crew/equipment: At the Lamaze class just before Ross and Susan argue about who should lie on the floor, a boom mic can be seen in the top left corner of the screen. (00:08:50)
The One with the Stoned Guy - S1-E15
Continuity mistake: After Chandler walks in on Ross and Joey talking dirty, Ross is holding his right hand up as he and Joey start to explain to Chandler. In the next shot his arm is by his side. (00:13:10)
The One with the Candy Hearts - S1-E14
Continuity mistake: Just before Carol and Susan enter the restaurant, Ross reaches for the menu with his left hand and his right hand is under the table. In the next shot his right hand is holding onto a cup on the table. (00:11:20)
The One with the Boobies - S1-E13
Continuity mistake: After Phoebe tells everyone she broke up with Roger, Monica has her legs crossed and Rachel has them uncrossed. In the next shot, Monica's are now uncrossed and Rachel's are crossed. (00:20:50)
The One with George Stephanopoulos - S1-E4
Continuity mistake: After Rachel speaks to her pregnant friend, they manage to swap places between shots. (00:05:50)
The One with the East German Laundry Detergent - S1-E5
Continuity mistake: At the start of the episode when Ross says, "Multiple orgasms", you can see Chandler's boot is not resting on his knee. In the next shot it has appeared from nowhere. (00:00:55)
The One with All the Poker - S1-E18
Continuity mistake: When Rachel finds out she has an interview she is holding the letter in her left hand. When the shot changes, the letter is in her right hand. (00:09:05)
The One with the Boobies - S1-E13
Continuity mistake: When Phoebe's boyfriend is talking about Chandler at the coffee shop, the cookie he is holding jumps from his left to his right hand in an instant between shots. (00:03:20)
The One with Mrs. Bing - S1-E11
Continuity mistake: In the final scene Rachel passes out copies of her draft for her book. She gives out all her copies and asks for their opinion. However, near the end of the scene after waving her arms around empty handed a copy of her script magically appears in her hands. (00:21:10 - 00:21:45)
The One with Two Parts: Part 1 - S1-E16
Continuity mistake: When Chandler tries to fire Nina, he holds his left hand to his face. In the next shot he is holding his right hand up. (00:10:20)
The One with the Dozen Lasagnas - S1-E12
Continuity mistake: During the song at the beginning of the episode, keep your eye on Ross's mug. He is holding it in his lap, then there is a shot of Monica with Ross's empty saucer on the table. In the next shot, the mug has appeared on the saucer. (00:00:30)
The One with Mrs. Bing - S1-E11
Continuity mistake: When Joey asks Ross 'how could you let this happen' in the hall, his sleeves are down to his wrists. In the next shot, they are rolled up. (00:10:25)
The One with George Stephanopoulos - S1-E4
Continuity mistake: When Rachel is explaining that she's not going back home, the friend with her arm on the back of the sofa behind her has her sleeve part the way up towards her elbow leaving a very prominent gap between the sleeve and bracelet. When the camera comes back to her the gap has now gone. (00:08:20)
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.