The One With The Ring - S6-E23
Plot hole: In the opening scene Phoebe and Chandler discuss how Phoebe knows Chandler is going to propose: by walking in on him whilst he was looking at a ring catalogue on the toilet. However, in the previous episode Chandler leaves the apartment right after he found out about Monica booking the wedding slot (on the answerphone) and doesn't come back until he 'freaks out' at Monica and then it is revealed that it was just put on and Phoebe is in on the plan. It doesn't add up, as Chandler would have had to have been looking at the catalogue between hearing the message and deciding to propose, in the same afternoon when he wasn't even in the apartment.
Suggested correction: Chandler decided at some point before the events of TOW Paul's the Man to propose to Monica (and that's when Phoebe walked in). He likely got Phoebe the passes to the museum (because he's the one that said Ross wouldn't be interested). If you look at the episode again, yes, he is freaking out-ish, but this is to fake out the audience. Also, he's "not the groom" because he hadn't proposed yet.
The One Where They're Up All Night - S7-E12
Revealing mistake: When Ross is shimmying down Joey, who is hanging onto the fire escape, you can see in his sleeves there are attachments keeping him in place. (00:20:33)
The One With The Flashback - S3-E6
Continuity mistake: When Chandler drops the cue ball by Rachel and her friends, the pool cue on the pool table is straight. When he speaks to her, it is suddenly at a 45-degree angle. The chalk cube and blue box also change position.
Audio problem: At the start of the episode, when Monica is reading the review in the newspaper, you hear her say 'turn to page 153', but if you look at her mouth, she actually says a number ending with 5.
The One Where Ross Meets Elizabeth's Dad - S6-E21
Continuity mistake: When Rachel is reading Chandler's horoscope, his arm goes from resting on the top of the couch around Monica to crossing his arms and back again between shots.
The One Where Ross and Rachel...You Know - S2-E15
Plot hole: Rachel says she didn't want to wear her glasses on their first date. Rachel doesn't wear glasses.
The One With All The Resolutions - S5-E11
Continuity mistake: Rachel mentions "the big thing," so Joey sticks his fingers in his ears to block her out. When Rachel pulls on his arms, the only things on the table are Joey's bottled drink, crayons, and coloring paper. In the next shot, we see Rachel's arms and she's not holding anything. It cuts to the next shot facing Joey, as he says, "Well then, it wouldn't be a secret, so yeah, that would be OK," and now there's a drinking glass on the table. Rachel removes it in the next shot.
The One With All The Resolutions - S5-E11
Continuity mistake: At the start, when the countdown hits 3-2-1, there's a closeup facing the TV, and in the TV's reflection the couch and armchair are both quite empty, but in previous and following shots both have people seated.
The One Where Rachel is Late - S8-E22
Continuity mistake: At the end, when Rachel and Ross leave for the hospital, Rachel grabs the keys. In the close-up, when Rachel asks, "Do you think we have time?" she holds the keys up in her left hand while Ross holds her empty right hand. It then cuts to a medium shot, and the keys are now in Rachel's right hand, the same hand Ross holds. (00:20:40)
The One Where Rachel is Late - S8-E22
Other mistake: Rachel's water breaks, but her skirt is completely dry.
The One Without The Ski Trip - S3-E17
Continuity mistake: At the start, just as Rachel is leaving Joey's apartment after mentioning the tickets she's got, Joey stops her and she turns round. Her hands are clasped together in front of her chest in one shot and by her side in the next. (00:04:00)
The One The Morning After - S3-E16
Continuity mistake: When Rachel asks, "When did Chloe leave?" the paper Ross is holding changes direction. Note the title of the paper: The New Yorker. (00:13:30)
The One With The Football - S3-E9
Continuity mistake: When they are outside for the first time, you see a shot from behind Monica, Joey, and Chandler. Monica then says, "Bring it in," and the shot changes. However, all 3 are now in different poses to what they were in before. (00:04:40)
The One With Phoebe's Ex-Partner - S3-E14
Continuity mistake: When Phoebe says you never run on a barge, her hand changes position on the table between consecutive shots. (00:06:50)
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 And Rachel Take A Break - S3-E15
Visible crew/equipment: When Ross is on the phone to Rachel, near the start, just as he walks into the living area, a stage light is visible above him (only visible in fullscreen version). (00:06:10)
The One Where Monica and Richard Are Just Friends - S3-E13
Continuity mistake: When Monica is dabbing Richard's shirt, the way she is holding the cloth changes between shots. Note the amount over her fingers. (00:08:50)
The One With Ross's Inappropriate Song - S9-E7
Continuity mistake: When Chandler turns around and Joey watches the football game, the door to Chandler and Monica's room is open. However, when Joey sees the sex part of the tape in the next shot, as Chandler is about to turn around and the TV screen is visible, the door is shut. (00:14:29)
The One In Massapequa - S8-E18
Continuity mistake: When Monica shows Chandler the photo of Chi-Chi, as she says, "It's good stuff, huh," in the closeup Monica takes hold of the photo with her raised empty right hand, but in the next wide shot Monica is holding a Sharpie in her right hand and the photo is in her raised left hand. (00:02:25)
The One With The Stain - S8-E7
Continuity mistake: After Gunther responds to Ross with the biting "ezels" retort, it cuts to Monica and Brenda in the living room, and when Monica falls off her chair, the rug and blue pad underneath are suddenly rolled up at the corner, then the rug is properly flat. (00:11:15)
