The One With Rachel's Inadvertent Kiss - S5-E17
Revealing mistake: When Ross is doing his "Watching TV" bit, there is a brief shot of the blank screen that he is sitting on the sofa pretending to watch. In the screen's reflection, it is clear that the sofa is empty. (00:03:55)
The One Where Underdog Gets Away - S1-E9
Revealing mistake: Whenever Monica's apartment is shot from the point of view of the balcony looking in, fake walls have to be put up across the room to cover the open space (since there is no wall there usually). When the friends are looking out the window at Ugly Naked Guy and his girlfriend in this episode, you can see that the rear wall does not extend nearly far enough - there is a large black space behind Monica. (00:19:25)
The One In Barbados, part 2 - S9-E24
Visible crew/equipment: When Ross and Charlie are hiding behind the the plant the camera switches to a wider shot of the the three scientists looking around.When it does this the microphone is very visible at the top of the screen. (00:45:00)
The One with the Ick Factor - S1-E22
Visible crew/equipment: In the scene when Rachel is sleeping next to Ross, you can see part of the mattress behind the sofa which cushions his fall later on when he trips. (00:20:40 - 00:22:55)
The One Where Rachel Finds Out - S1-E24
Visible crew/equipment: When Rachel is on the balcony with her date, after she kisses Ross and says, "Wow!", the shot changes back to her date. While he is saying, "Exactly" you can see a camera man on the left side of the screen. Then when the shot changes to show Rachel and her date you can see him move out of the shot. (00:19:45)
Revealing mistake: At the very beginning, as Gunther complains to Joey about talking to his friends, he then says something like, "This guy has been waiting for his coffee for ten minutes". He passes a mug to Joey, but it is very clear the mug is empty. (00:01:40)
The One With Phoebe's Ex-Partner - S3-E14
Continuity mistake: When Joey is telling his story about throwing Ginger's wooden leg in the fire, when he gets to the part about him, Ginger and the dog Pepper falling asleep in front of the fire, a large section of her hair falls in front of Phoebe's face. In the next shot it's gone;, however her hands are visible the whole time and she has not pushed the hair back. (00:08:05)
The One With Phoebe's Husband - S2-E4
Continuity mistake: In the scene where Rachel is telling Ross it is sexy for a man to wait before having sex, the cups behind Ross change color: red to green to red and back again. (00:08:10)
The One With Ross's Sandwich - S5-E9
Continuity mistake: In the scene where Joey has just brought home his date, he jiggles the door handle, which makes Monica and Chandler run off into Chandler's room. Chandler kicks a circle cushion off the mat, but when the camera cuts back, it's on the mat again, and then off the mat again when Rachel walks in. A red cushion also moves. (00:09:10)
The One With the Sharks - S9-E4
Continuity mistake: In 'The One With The Shark Porn' (Series 9), when Chandler and Monica are talking about his supposed shark obsession, Chandler's collar switches from up to down depending on the shot. It switches several times during the scene. (00:20:30)
The One With Rachel's Going Away Party - S10-E16
Continuity mistake: The level of beer in Ross' bottle goes up and down between shots as he's talking to Joey at the kitchen table. (00:12:00)
The One With the Breast Milk - S2-E2
Visible crew/equipment: In the first part of the episode, there is no ceiling above the secret closet, revealing a whole lot of stage lights. (00:01:20)
The One With Joey's New Girlfriend - S4-E5
Audio problem: In the sequence where Chandler chases Kathy down the street, there is a moment, shortly after he walks into the man with the hotdog, where he shouts her name, but his lips don't move at all. (00:11:25)
The One With The Video Tape - S8-E4
Continuity mistake: When we see the video, notice Rachel's hair. It is the same length as it is throughout season 8, but her hair is supposed to be the short bob she had in season 7 since it took place then. (00:17:00)
The One With The Cooking Class - S8-E21
Visible crew/equipment: In The One With The Cooking Class, just after Ross gets back from his date, a boom mike is hovering over Rachel's head. (00:17:25)
The One With Ross's Denial - S6-E3
Continuity mistake: When Monica and Chandler are eating, Monica's plate holds a sandwich and chips. When Joey comes in, Monica's plate contains no chips, and when he leaves the chips are back again. (00:04:00)
The One With The Cake - S10-E4
Visible crew/equipment: When Monica is talking to Chandler about waking Emma up, as she walks over to him, crew lights are visible in the top left corner of the screen. (00:05:35)
The One With Phoebe's Cookies - S7-E3
Continuity mistake: While trying out different recipes, at one point Monica's holding a cookie in her hand. It's a whole cookie, but when the angle changes, suddenly a chunk is missing. (00:13:00)
The One With The Blind Dates - S9-E14
Factual error: Monica takes an ovulation test to see if she is still ovulating. The ovulation test only works before you ovulate (usually 24 to 36 hrs), to detect the LH surge that comes before you ovulate. Once you ovulate that surge is gone and the test will not work. (00:08:20)
The One With Rachel's Assistant - S7-E4
Visible crew/equipment: When Rachel holds up the Polaroid she took of her assistant, it appears to have been one of the actual photos taken in the earlier scene; you can see the edge of the set behind him, and the overhead lights in the black space to the right of the photo. (00:07:40)
Answer: The statements that she's contradicting (that it is common, it happens to every guy, and it's not a big deal), are the things that a woman commonly says to a man who is suffering from erectile difficulty, typically to assuage his bruised ego. However, most men do not believe that these statements are true, as evidenced by Chandler's outburst. He's so caught up in the proof that women are lying about it that he gives himself away.
Rooster of Doom