The One with the Evil Orthodontist - S1-E20
Other mistake: This is the episode where a guy across from Monica's apartment is spying on them. Joey says he caught him spying into his and Chandler's apartment yesterday. This is impossible considering the layout of the building i.e. the fact that the only part of Joey and Chandler's apartment which faces toward the spying guy has the stairwell and hallway blocking it from view (not to mention the protruding part of Monica's apartment). There is another window in Joey's apartment but it faces completely the wrong direction. The bathroom has no windows. The angles just don't add up. (00:00:40)
The One Where Rachel Finds Out - S1-E24
Other mistake: When Rachel leaves the apartment to pursue Ross to the airport, she is turning to the left when she exits the apartment. The stairs are to the right.
The One With Ross' New Girlfriend - S2-E1
Other mistake: After Rachel takes the phone from Ross and hangs up on Julie, when she's sitting at the table there's a bottle of Evian water in front of Monica with part of its brand name covered - the letters "e" and "n" are whited out leaving "via" on the bottle.
The One Where Ross Finds Out - S2-E7
Other mistake: When Rachel leave her message on Ross' answering machine she mentioned the name Michael after 17 seconds and "I'm over you" after 25 seconds. When Ross listen to the tape he asks "Who is Michael ?" after 8 seconds. Rachel flips the phone out of his hand after 18 seconds so he couldn't have heard her "I'm over you." (00:10:35 - 00:12:50)
The One Where Joey Moves Out - S2-E16
Other mistake: When Rachel is showing Phoebe her heart tattoo, the tattoo isn't dressed and covered, nor is the skin around it red or swollen, despite the fact she just finished getting it. (00:14:09)
The One With Two Parties - S2-E22
Other mistake: In the scene where Rachel is talking to Chandler in the hall, after she says "the 4th of July", it cuts to a shot from behind Rachel's head. If you look on the right hand side of the screen, you can see a piece of wood in the foreground. This probably came from Joey and Chandler's doorframe, through which this view would have been filmed. In addition, this door was supposed to have been closed throughout the entire duration of this scene. (00:17:55)
The One With Two Parties - S2-E22
Other mistake: When Ross is at Monica's party getting Mr. Green's glasses and cigarettes he bumps into Mrs. Green and ends up having to come up with an alibi for the glasses and cigarettes. He then puts the glasses on, puts a cigarette in his mouth and says 'In fact I'm gonna go out into the hallway and fire up this bad boy'. At this point he walks past Rachel but he stops still as if frozen mid-step just before the shot cuts to him walking out into the hallway.
The One With The Princess Leia Fantasy - S3-E1
Other mistake: When Phoebe makes fun of Ross' Princess Leia fantasy with the rolls, Rachel tries to stop her; the shots used are the same action, just from different angles. Look at Rachel's hands and the towel in her hand when Phoebe puts the rolls by her ears.
The One Where No One's Ready - S3-E2
Other mistake: When Monica beeps into Richard's machine and changes the outgoing message, she always presses the same two buttons when trying to interact with his machine, but gets a different result each time. (00:19:00)
The One With Frank Jr. - S3-E5
Other mistake: Chandler tries to open the door that leads to his room, but Joey has sawed the door in half so only the upper half opens, and Chandler then falls over the bottom half. He has to hit it with some force to fall over it, but it doesn't budge an inch. (00:00:50)
The One With Frank Jr. - S3-E5
Other mistake: Monica doesn't realise what the floor looks like under the hamper, but due to her obsessive cleaning she would know this for sure.
The One With The Flashback - S3-E6
Other mistake: When Phoebe's holding the box of Nabisco Nilla wafers, the Nabisco logo has stickers and paint hiding it and the Nilla is also partially covered so it reads "Villa" wafers.
The One With The Giant Poking Device - S3-E8
Other mistake: When Monica and Joey are holding containers of Ben and Jerry's, the brand name reads "En and Jer" and other parts of the containers have also been concealed, but we can still recognize the old Wavy Gravy in Monica's hand.
The One With The Football - S3-E9
Other mistake: The accent of the Dutch woman is not a Dutch accent at all. It appears to be Scandinavian. (00:07:00)
The One With The Dollhouse - S3-E20
Other mistake: The dollhouse is only partially burned when Ross takes it into the bathroom to extinguish it. When he shows it to Phoebe it's completely blackened and destroyed. He and Monica wouldn't have just let it burn; they would have extinguished it ASAP, and there's no reason why that wouldn't have been fast if they doused it in the shower.
The One With Ross's Thing - S3-E23
Other mistake: When Ross goes to see Guru Saj, he has his 'thing' removed. However, it is really obvious that Guru is not going anywhere near the thing, because you can see that Ross' shirt is still tucked into his trousers, and the Guru just rubs his hands along the shirt. (00:16:35)
Other mistake: When Phoebe breaks into the other Phoebe's house, after she mentions that the man on the picture is "Chuck Mangionne" the door behind her opens by itself. (00:19:40)
The One With The Jellyfish - S4-E1
Other mistake: When Chandler and Monica are sitting at the table after playing Gin, Chandler's bottle of Yoo-hoo is on the table, but the label reads "Yooh" because the brand name has been partially covered - the blue letters "oo" are yellow to match the background.
The One With The Ballroom Dancing - S4-E4
Other mistake: In the scene where Rachel is going to take out the trash, Monica tells her the garbage room is the 3rd door on the left. However, when Rachel comes back with the pizza box and Monica leaves for the garbage room, she leaves the apartment and walks towards the right - there are no doors that way, just the stairs. (00:00:50)
The One With The Ballroom Dancing - S4-E4
Other mistake: Right at the end of the episode, Phoebe's got a job interview. We see the outside of a massage parlour, but the name on the awning has been superimposed - it moves about a bit while the shot itself is still. (00:20:45)
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