The One With The Stripper - S8-E8
Continuity mistake: When Mona is saying thanks to Ross for showing her his rock collection she puts her hair behind her ear, then when she's leaving she puts it behind again.
Continuity mistake: Rachel and Monica are talking about Phoebe getting pregnant at the table. Rachel's hands change every time where the camera is showing them in a different angle.
The One With Phoebe's Cookies - S7-E3
Continuity mistake: When Chandler and Jack are placing their robes on the hook, they change positions when Jack looks at Chandler naked. (00:19:39 - 00:20:08)
The One With The Hypnosis Tape - S3-E18
Continuity mistake: When Monica serves cheesecake to Pete, she goes to put the lid back, but in the next shot the lid is not there. (00:07:16)
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 The Apothecary Table - S6-E11
Visible crew/equipment: When Rachel and Phoebe are talking in front of the Pottery Barn window, a wooden set wall covered in several signs is visible on the far right in the shots of Rachel.
The One with the Dozen Lasagnas - S1-E12
Other mistake: After Carol asks Ross if the lasagna is vegetarian, the camera briefly goes out of focus before Ross says "I'm pretty sure that it is." (00:05:00)
The One With The Proposal, part 1 - S6-E24
Other mistake: Joey bids on a Catalina 22 yacht, but the picture, and the yacht he and Rachel are on at the end, is a Catalina 18.
The One with Two Parts: Part 1 - S1-E16
Visible crew/equipment: When Phoebe knocks on Joey's door you can just see 2 orange T markers on the floor. (00:22:10)
The One with the Boobies - S1-E13
Continuity mistake: When Joey's mum explains that every day is like her anniversary, her hands are outstretched. Camera cuts and they are lowered. (00:18:20)
The One with the Boobies - S1-E13
Continuity mistake: The way Rachel is sitting when discussing seeing Chandler naked is constantly changing. (00:07:00)
The One with the Dozen Lasagnas - S1-E12
Continuity mistake: Second time we see Monica score on the foosball table, she spins the rod closest to the goal. The camera changes and the ball is hit from the rod furthest away from the goal. (00:17:35)
The One with Mrs. Bing - S1-E11
Continuity mistake: At the hospital, the positions of the balloons Monica brings change instantly. Note the blue one. Its height changes drastically from below to level with the yellow one. (00:11:30)
The One with the Monkey - S1-E10
Continuity mistake: When Phoebe asks the guys if there is something they would like to share with the group, David goes from looking at his friend to looking at Phoebe between instant cuts. (00:05:05)
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 Underdog Gets Away - S1-E9
Continuity mistake: When Rachel turns up with her tickets, Chandler has his hand on his hip. As Rachel walks off however, his arm is behind her. (00:12:00)
Continuity mistake: When Ross is reading the book he shows it to Phoebe who passes it back. Then without turning the pages he passes it to Chandler but the pages are different now. (00:07:20)
Continuity mistake: When Joey asks how the play was, Monica's grip on her program changes between shots. Note the gap between her hands. (00:04:20)
The One with Two Parts: Part 1 - S1-E16
Continuity mistake: Towards the end, as Joey is leaving Central Perk, Rachel's posture goes from leaving over the back of the sofa with her hands clasped to standing up with her hands on the back of the sofa. (00:18:15)
The One with Two Parts: Part 1 - S1-E16
Continuity mistake: When Rachel says about the name being the same in Spanish and English, the way she holds her chopsticks changes between angles. (00:06:10)
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