Continuity: 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.

Revealing: When Phoebe phones Emily's mother to say she is Ross' pediatrician (or something like that) look out the window behind Phoebe. The buildings are moving slowly from side to side.

Revealing: When Chandler and Monica (and later Joey) are talking on the plane on the way back from London, the little display screen (showing a map of the Atlantic and coastlines) in front of Monica's seat shows the little grey plane indicating their position and direction. The plane is facing east, as though they are travelling towards London, but they are supposed to be flying back to New York.

Continuity: In the Central Perk scene where Rachel is telling Ross she loves him, Ross is sitting at the small round table. The blue cup and the white cup with the lid move positions throughout the scene.

Continuity: There is a scene in Central Perk where Rachel confronts Chandler about all the kissing he's been doing. She raises her hands up in front of her and tells Chandler to hold on to stop him from getting up from the couch. As he goes to sit back down on the couch she lowers her hands to her lap. The shot cuts to an angle behind Rachel's chair and she is lowering her hands again.

Factual error: When Monica is in the bath with Chandler, Joey comes in twice, forcing Monica to hide under the bubbles: first he asks Chandler if he wants some chicken, then again when Chandler calls him back and Chandler's giving Monica's order, with Monica still hidden under the bubbles. Somehow, Monica supposedly hears Chandler requesting a soda and nudges or pulls him or something to indicate he was going to get the wrong kind. But no way she could hear him under the water (stick your head in a tub and have your friend recite the alphabet, and see what I mean).

Continuity: In the scene after Monica pretends to drop socks in the hallway in order to prevent Rachel from telling Ross she still loves him, Rachel goes back into the apartment and locks Monica out. Monica then starts to pound on the door with her bare left hand. The scene changes to the apartment and Ross opens the door to let Monica in. All of a sudden Monica is pounding the door with her right hand wrapped in a sock.

Continuity: When Phoebe says she is going to "pack her ass off" she walks toward the coffee house door, and they cut to another scene quickly and then back to the door and Phoebe has disappeared. She did not have time to make it to the door and out.

Continuity: In The One With All The Kissing, Phoebe grabs a photo of the other 5 by the Tower of London. When we see a shot of her a few seconds later drawing herself into the photo, it's a different photograph.

Continuity: When they enter the hospital, Phoebe says, "Someone should call Frank and Alice, and my mom," and Ross searches his pockets(presumably for his cell phone). But in the next shot, his hands are not in his pockets.

Factual error: Joey always grabs his back when he gets his pain from his kidney stones. This is a classic referral pattern for pain when the stones are in the kidney. However, the doctor says that the kidney stones were too close to the bladder. Stones in the ureters classically refers the pain to the groin area.

Continuity: When Alice runs towards Frank in the waiting room, there are at least two people sitting on the couch next to Frank. Immediately afterward, when Frank and Alice lie down on the couch, kissing, these people have disappeared.

Continuity: Monica comes to get her pan back from Chandler, and when she opens the door, the magna doodle pen is hanging down. The shot changes and it is attached to the board; it changes again and it is hanging once more.

Continuity: In the opening scene where Rachel is checking the mail and is walking over to Monica's room, she has a pair of pumps on, then once she has walked in on Monica and Monica runs after her to say she was taking a nap, Rachel is wearing a pair of backless high-heeled sandals, then when Joey and Ross come in, Rachel is wearing the pumps again (we see this when Ross says "I had to talk loud because the movie was loud").

Other: When Ross tells Rachel he can't see her anymore, the door to Monica's room is open revealing a completely blank and empty room.

Continuity: Rachel and Phoebe are in the Central Perk, talking about leaving the group, and a jacket and a handbag are hanging on the arm of the chair behind Rachel, slightly to her left. Between shots it changes from just the jacket, then just the handbag and so on. This continues throughout the scene when Ross comes in and Phoebe leaves. As she gets up you see both again, however Rachel does not move enough to just show one and hide the other.

Continuity: In this episode, they say the reason Kip was phased out was because he dated Monica and they broke up badly. However, in the first season (in the "Dozen Lasagnes" episode) Chandler says Kip left because he got married.

Continuity: When the group is in the coffee house discussing Kip there is a bag on the table in front of Monica. When Rachel enters she places her bag on top of the bag already sitting there. Toward the end of this scene Rachel's bag then disappears and only the original bag is now sitting there.

Plot hole: In TOW Ross tells Rachel he cannot see her following a promise to Emily, the rest of the friends go into Monica's bedroom. Joey hauls out a box from under the bed, saying that he's been hiding it there since Ross said the wrong name at the wedding. Surely Monica, with her obsession for keeping the place clean, would have noticed a box under her bed?

Continuity: Ross is in his apartment, and he is saying he will miss it. Throughout the scene, the phone appears and disappears in the charger cradle.