The One With The Triplets - S5-E3
Factual error: Joey always grabs his back when he gets his pain from his kidney stones. This is a classic referral pattern for pain when the stones are in the kidney. However, the doctor says that the kidney stones were too close to the bladder. Stones in the ureters classically refers the pain to the groin area. (00:02:40)
The One With The Triplets - S5-E3
Continuity mistake: When Alice runs towards Frank in the waiting room, there are at least two people sitting on the couch next to Frank. Immediately afterward, when Frank and Alice lie down on the couch, kissing, these people have disappeared. (00:16:30)
The One With The Triplets - S5-E3
Continuity mistake: When they enter the hospital, Phoebe says, "Someone should call Frank and Alice, and my mom," and Ross searches his pockets(presumably for his cell phone). But in the next shot, his hands are not in his pockets. (00:00:05)
The One With The Triplets - S5-E3
Revealing mistake: When the doctor says, "Here comes the head," it is very obvious that there are feet coming out. (00:14:50)
The One With The Triplets - S5-E3
Visible crew/equipment: In the scene with Joey filming Phoebe and Phoebe saying, "Please don't hurt me," Joey zooms out and you can see the camera that is just about to film them. (00:00:35)
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