The One Where Everybody Finds Out - S5-E14
Continuity mistake: In the scene where Chandler turns on music when he and Phoebe are going to "have all the sex" you see Phoebe's arm begin to move in the right corner of the screen. When it cuts to her she has not yet begun dancing, and when he goes to turn the music on again it is a duplicate clip from the initial shot.
The One With Joey's Bag - S5-E13
Continuity mistake: When Phoebe realises she just met her dad she turns to her friends to share the news, and in the closeup she's holding a pair of 3D glasses in her right hand and Monica's holding a pair in her left hand, but in the next wideshot both of those glasses have vanished. (00:09:15)
The One With Joey's Bag - S5-E13
Continuity mistake: When Chandler speeds up the timer for his turn he places the timer down at the right side of the pillow, but it's at the opposite side of the pillow when he lies down. Then before Monica starts giving Chandler his massage, she sets the timer and places it near the foot of the bed which we see in Chandler's closeup, but in the next shot when she says, "Say goodbye to sore muscles," oblivious to Chandler's pain, the timer is lying by the pillows behind her, near the head of the bed. Note, in the "uncut scene" version, Chandler grabs the timer to speed up his torture, and Monica takes it out of his hand thinking he was going to add more time, then she places the timer behind her. (00:00:25)
The One With All The Kissing - S5-E2
Visible crew/equipment: When Rachel is telling Monica, Chandler and Phoebe how Ross abandoned her at the airport, when she walks towards the TV a boom mic is briefly visible at the top left of the screen.
Audio problem: When Rachel and Ross are in Central Perk, Ross says "Well there's this one thing." Then it cuts to a shot of the side of his head where he says "Okay" and it doesn't match his lips.
The One With The Ride-Along - S5-E20
Plot hole: When Rachel picks up the box of photos they all fall out, because the box isn't sealed with tape or even folded properly. But there's no way for that to have happened. Monica would have brought the box from somewhere and put it on the couch, and the photos would have fallen out then, and she would have fixed it (this is Monica, after all.) The only way for this to have happened is if she put the empty box on the couch, unfolded/unsealed, and then put photos in it - which Monica would not do.
The One With Joey's Big Break - S5-E22
Other mistake: When Ross is questioning Phoebe on why she is mad at him, he has his blue sweater on backwards.
Suggested correction: So he has his sweater on backwards. That's a character mistake, not a movie mistake.
The One Where Everybody Finds Out - S5-E14
Continuity mistake: When Monica and Chandler come in to ask Joey about Pheobe knowing about their relationship he throws the Hugsy teddy behind him. In the next shot we see behind the chair and Hugsy is not there.
The One Where Ross Can't Flirt - S5-E19
Continuity mistake: When Ross first tries to flirt with the pizza girl he has money in his hand. When Chandler walks over he gives his own money for the pizza, she leaves, and Ross still has his money. In the next shot when he shuts the door, his hands are empty, then it is back in the next shot when Ross yells at Chandler.
The One After Ross Says Rachel - S5-E1
Continuity mistake: Between season 4 and season 5 some of the furniture in Chandler's and Joey's hotel room is changing. In TOW Ross' Wedding the three big pictures over the beds show dark spiky plants like ferns and palm trees (as can be seen in the scene where Joey shows Chandler the video with Fergie). In this episode these pictures are completely different - they show a red flower, a sunflower and a dark green plant. The two pictures next to the door are now much smaller in bigger frames and the lamp on the night table between the beds which had a white shade in season 4, now has a black shade. The nightstand between the two beds also has a different shape.
The One With Joey's Bag - S5-E13
Visible crew/equipment: When Joey walks into Monica and Rachel's apartment to tell the gang he didn't get the part thanks to the bag, as he approaches the couch you can see the end of the stage over Joey's right shoulder. (00:21:15)
The One In Vegas, Part 2 - S5-E24
Continuity mistake: When Monica puts the blue jumper up her dress, she lifts it up and you can see she is wearing black jeans underneath. The next scene shows her running off without the jeans underneath her dress. (00:18:55)
The One Where Ross Moves In - S5-E7
Continuity mistake: Rachel tells her neighbor Danny that she doesn't know anything about sailing, but later in the series, Rachel teaches Joey how to sail after he wins a boat at a silent auction. She says she learned sailing from her father while growing up.
The One With All The Kissing - S5-E2
Continuity mistake: A few days after the friends have returned to New York following Ross' wedding, Monica's hair is suddenly about three inches longer and a completely different style than it was in London. It was previously just above her shoulders in a sleek "pageboy" style. Once back home, it is much bushier and longer, well over her shoulders. This was obviously due to Courtney Cox growing her hair during the break in-between Season 4, which ended with the Ross/Emily wedding debacle, and Season 5. (The first episode of Season 5 was filmed the previous season and was Part 2 of Ross and Emily's wedding).
The One Where Ross Can't Flirt - S5-E19
Continuity mistake: In the scene where the gang is watching Joey's "substitution" video, you can easily see the reflection on the television that no one is sitting on the couch, but when the camera goes back to the gang, they're sitting down on the couch. (00:19:30)
The One With All The Kissing - S5-E2
Visible crew/equipment: When Rachel tells her date she's going to have to take a rain check and goes back into the apartment, as she opens the door you can see a cameraman standing inside the apartment. (This is only visible in the broadcast version, not DVD or widescreen). (00:10:45)
The One With All The Thanksgivings - S5-E8
Continuity mistake: The emergency room doctor's rubber gloves come and go between shots.
The One Where Ross Moves In - S5-E7
Revealing mistake: When Joey and Chandler go in the bedroom to talk, Joey suggests they play a game of foosball. There is no ball when they start playing - quite noticeable when Joey " scores" a goal.
The One With Ross's Sandwich - S5-E9
Character mistake: Joey tells Chandler and Monica that Rachel found the underwear in Monica's sofa. It was actually Phoebe who pulled them from the sofa and held them up.
The One Where Ross Moves In - S5-E7
Revealing mistake: During Danny's party you can see Monica's apartment through the gap between the door and the wall, despite the party taking place on a lower floor. This is because they just reused the set for the hallway to save having to build a new set for the "lower floor."
