The One With Rachel's Phone Number - S9-E9
Continuity mistake: In the scene where Joey is sitting in front of his door with the baseball bat, the bar stool is directly in front of his door. When he stands up the chair does not move. However when he and Chandler come back to the hall the chair is over in the corner next to his door. (00:16:00 - 00:19:35)
The One With Rachel's Phone Number - S9-E9
Continuity mistake: Near the end when Rachel runs after Phoebe and Mike to ask Mike if the guy from the bar called, she leaves the apartment with her bag, which she places over her left shoulder. When she is talking to Mike the bag is gone, and then when she returns to the apartment she has her bag again. (00:20:30)
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