The One With The Jellyfish - S4-E1
Audio problem: When Phoebe is knocking on her sister Ursula's door to tell her about finding her birth mom, the third knock is heard a split second before you see Phoebe's hand action. (00:12:15)
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 Embryos - S4-E12
Audio problem: When Rachel is banging on the door at the start, the sound does not match the actions. (00:01:00)
The One With Rachel's Crush - S4-E13
Audio problem: In the scene where Rachel walks into the guy's new apartment and they start talking about Joshua, it cuts to a shot of her in profile as she says "It's just so frustrating". Her mouth doesn't move as she says the words. (00:09:40)
The One With Ross's Wedding, part 2 - S4-E24
Audio problem: When the wedding officiant says "take thee, Ross" his lips don't move. (00:20:35)
The One With Ross's Wedding, part 2 - S4-E24
Audio problem: Toward the end of the episode Ross' Dad and Emily's dad are arguing. Ross comes between them and you can hear the audio saying"From now on everybody gets along!" But it does not match up with the movement of Ross' lips.
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