The One with the Sonogram at the End - S1-E2
Continuity mistake: When Rachel loses the ring near the beginning, Chandler and Joey get off a chair to help look. But then the shot cuts to Monica, and behind her you can see Chandler at the fridge without enough time to get there. (00:05:40)
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.
Audio problem: Any scenes outside Central Perk always sound as if they're on a set (which let's be honest, they are) - the sound is often muted and footsteps on the pavement have a very slight echo to them.
Visible crew/equipment: In the scene where Chandler is talking to Rachel and Ross about how Janice thought that he had somehow called her fat, if you watch Monica's closet in the back, you can see the shadow of someone walking past, under the door. (00:05:20)
The One With Ross's Inappropriate Song - S9-E7
Visible crew/equipment: When Monica comes home at the end, as Joey pulls her down on top of Chandler as to protect her eyes from seeing the tape, you can see a knee pad on Courteney Cox's knee, under her skirt. (00:14:20)
The One With The Halloween Party - S8-E6
Continuity mistake: When Phoebe is talking to Ursula's fiance Eric, he is wiping sweat off his face with a napkin. He puts the napkin to his eye and then in the next shot it changes to the other eye without him having enough time to change it. This happens again when at one point he's wiping his eye and then suddenly his forehead. (00:07:45)
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 Thumb - S1-E3
Factual error: The show is set in New York. Joey was a cast member on Days of Our Lives, which is filmed in Los Angeles, but is still always around.
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 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 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 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.
Later in that scene, Ross references The Shining as a book Joey loves that stars Jack Nicholson. Therefore, it's safe to assume that Joey has seen the movie and the audience could infer that he may confuse the two often enough for Ross to reference it that way. This might just be another Joey mistake (which he has many) vs a factual error of the show.
The One with the East German Laundry Detergent - S1-E5
Visible crew/equipment: When the horrible woman enters, the boom mike is visible in the mirror at the top of the screen. (00:10:10)
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)
