The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: While Rachel is having her baby she grabs Ross by the shirt and says 'you do it for me' in the next shot her hand is no-where near Ross. She couldn't have put her arm down that quickly. (00:33:50)
The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: When Phoebe and Ross are standing in front of the screen looking at all the babies and talking about why He and Rachel aren't together, some of Phoebe's hair is in front of her shoulder on the right hand side then the shot changes looking over Phoebe's shoulder at Ross. Then when you see Phoebe again her hair is behind her shoulder yet she has not moved or touched her hair. (00:45:00)
The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: When Ross is telling Chandler that Janice is there and she's contracting Chandler can be seen putting his hands on his face. In the very next shot his hands are by his side again. (00:02:50)
The One Where Rachel Has a Baby, part 2 - S8-E24
Continuity mistake: When a nurse is putting Emma to bed we see that Emma is nicely wrapped up in a blanket. The shot then cuts and Emma's right arm is sticking out the top of the blanket.
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