
The One With The Bullies - S2-E21
Visible crew/equipment: When Phoebe goes to visit her father, there is a little dog outside. Phoebe gets back in the car and the dog jumps up the side of it. When he finally gets part way through the window, the top of the dog-handler's head is visible through the car window. (00:07:00)
The One With The Embryos - S4-E12
Character mistake: After the guys have beaten the girls in the quiz, Rachel refuses to move apartments and Monica says: "If we had lost, we would have made them get rid of the birds." But they did lose. That's why the guys have got their apartment. She should have said if we had won.

The One Where the Monkey Gets Away - S1-E19
Continuity mistake: After Marcel has escaped from the basement, he is eating a banana as a pair of arms reach out to grab him. These arms are supposed to belong to Mr Heckles, their weird neighbour, however the arms belong to someone young, large and hair free. (00:16:10)
The One With The Flashback - S3-E6
Continuity mistake: When Ross and Phoebe are in the bar and get on the pool table to start kissing, Ross moves the pool balls out of the way, but two remain. As Phoebe lies down, the 9 ball is next to her left shoulder. The shot cuts closer and it is the 13 ball, then cuts back and it's the 9 ball again. (00:19:40)
The One With Monica's Thunder - S7-E1
Continuity mistake: The beginning to series 7 takes place right after series 6 ended, basically Chandler has only just proposed to Monica. Yet Monica's hair is visibly different; at the end of series 6 she had no fringe and a center parting, now she has a fringe. Also Chandler, is visibly thinner, with a gaunt face due to losing 20 lbs in between the two series. Rachel also has had a hair cut, her long extensions have been removed and she is back to her usual hair length.
The One With Rachel's Date - S8-E5
Continuity mistake: When Monica and Phoebe both confront Tim, they blurt out their news at the same time. In the three-shot he uncrosses his arms in surprise, but in the shot of Phoebe we can see he's still got his arms crossed. (00:17:00)
The One With Frank Jr. - S3-E5
Other mistake: Chandler tries to open the door that leads to his room, but Joey has sawed the door in half so only the upper half opens, and Chandler then falls over the bottom half. He has to hit it with some force to fall over it, but it doesn't budge an inch. (00:00:50)

The One After the Superbowl, part 2 - S2-E13
Continuity mistake: Chandler is talking to Susie (Julia Roberts) and a man is standing behind Chandler in a doorway. There is a cut to Susie, but when the camera goes back to Chandler the man is not there. Then he appears again. (00:03:20)

The One With The Prom Video - S2-E14
Visible crew/equipment: During the prom video, Monica, Rachel, and Monica's date Roy are standing in the living room. When Roy leaves the room saying, "I'm gonna kick Chip's ass," the camera follows him out, but as it's turning the boom mic operator is visible. He's kneeling on the floor sliding the mic toward the girls. (00:20:45)
The One Where They All Turn Thirty - S7-E14
Continuity mistake: Rachel is said to be the youngest in the group as they reminisce about their 30th birthdays, however this episode reveals that almost all of the characters ages have been inconsistent throughout the series. In Season 1, Joey is said to be 25. In Season 2, he says he is 28. In S7 E1, he says he is 31. In Season 1, Monica is said to be 26. In Season 7, she should therefore be at least 32. Rachel graduated high school with Monica, so she should also be about 32 in S7, not just turning 30. She would have been 26 in S1. But, in Season 4, she refers to herself as a "28-year-old cheerleader". Based on Season 1, Joey should actually be the youngest member of the group, not Rachel.

The One With The Routine - S6-E10
Visible crew/equipment: While Monica and Ross attempt to do the original end to their routine, instead of Monica catching Ross she jumps out of the way, and when Ross lands on the floor the corner of the crash mat can be seen. (Widescreen version).
The One Where Monica and Richard Are Just Friends - S3-E13
Factual error: Joey refers to several of his favorite parts of The Shining in 'code', including "all blank and no blank makes blank a blank blank, " which obviously refers to the "all work and no play makes Jack a dull boy" scene from the movie. However, that scene (and the one where Danny sees the two "blanks" in the hallway) is not found in the book; only in the movie. (00:13:55)
Suggested correction: I know they're talking about the book, but doesn't it actually make sense for Joey to be referencing the movie, even though the conversation is about the book? Considering the character, I don't think that's off at all. He's read the book, but he's obviously seen the movie, too.

The One With Rachel's Sister - S6-E13
Visible crew/equipment: After Jill comes to Monica's apartment, they are all around the table in the living room. As the camera is moving from Jill, to Monica and Chandler, who are sitting on the couch, a camera-man is visible in the kitchen behind them, complete with camera and trailing wires. (00:04:15)
The One With The Mugging - S9-E15
Continuity mistake: When Phoebe and Ross are 'mugged' it is dark and in the evening. However, when Ross tells Monica what had 'just' happens you can see that it is the middle of the day (00:07:45)
The One With Joey's Bag - S5-E13
Continuity mistake: When Phoebe is in the coffee house talking to her father and pretending to be the executor of her grandmother's will, after she says "lipstick and a daughter, big day for you" she folds her papers in half, but in the next shot they are unfolded and she then folds them again. (00:15:15)
The One With The Ball - S5-E21
Continuity mistake: In the interrogation room, the blinds behind Phoebe keep going from open to closed in different shots. (00:14:10)
The One With The Tea Leaves - S8-E17
Continuity mistake: When Ross opens Mona's door with the hidden key he only has to unsnap the door. Also, when Mona enters her flat a moment later she has to unlock the door. (00:10:50)

The One With The Engagement Picture - S7-E5
Revealing mistake: In the shot of the paper with the picture of Monica and Joey, the anouncement written there starts out fine, but near the end the middle part is just repeated again. (00:20:35)
The One After Ross Says Rachel - S5-E1
Continuity mistake: Monica and Chandler are piling their dinner plates with food while arranging to meet for a second quickie. Chandler's plate is stacked with various items when he agrees to meet Monica in the cellar, but when he tosses his plate back onto the table to rush off without eating anything, the plate is nearly empty. (00:04:45)

The One with the Dozen Lasagnas - S1-E12
Continuity mistake: When Rachel is talking with Phoebe about Paolo,. she unrolls some kitchen paper and uses it as a tissue. Initially she's holding two torn halves attached to the roll, then when saying "He's a pig" it goes to a whole sheet not attached to any others, then when she sits down it's a whole sheet attached to the roll again. Plus when Phoebe sits too, in some shots the paper is on the table, in others it's not. (00:15:20)