The One With Rachel's Other Sister - S9-E8
Continuity mistake: When Ross, Rachel, and Amy arrive at Monica and Chandler's apartment the table is set, and there are folded napkins in napkin rings on the plates at each place setting, but after Amy insults Joey all the napkins have vanished.
The One With the Male Nanny - S9-E6
Continuity mistake: When Mike and Phoebe are at Central Perk, Mike pulls his apartment key out of his pocket and he's holding the head of the key with the shank side up, but next shot he's holding the shank with the head side up.
The One With the Sharks - S9-E4
Continuity mistake: After Monica, Rachel, and Joey have been discussing Joey's problem Monica asks him if he thinks sharks are sexy, and when Joey asks about the Little Mermaid it cuts to Monica's closeup and the water bottle cap is on, but in the next closeup of Rachel the cap is off.
The One Where No One Proposes - S9-E1
Revealing mistake: While everyone's looking at Emma through the window, when Jack makes the comment about the first grandchild, someone in the background walks by and causes the hallway's set wall to wobble behind them.
The One With The Cooking Class - S8-E21
Visible crew/equipment: When Joey and Monica are leaving the cooking class, the teacher asks about the difference between hollandaise and béarnaise sauce, and in the next shot of Monica and Joey we can see the shadow of the moving boom mic at the top left side of the screen.
The One With Chandler's Work Laugh - S5-E12
Continuity mistake: During Ross and Janice's conversation in Central Perk, when Ross comments, "You're ending this with me because I'm too whiny?" both his and Janice's left arms are up, but it cuts to the next shot and it's their right arms which are up, then it happens again when Ross says, "I've become so whiny that I annoy you?! Janice!" they both have their right arms up, but next shot it's their left arms up.
The One Where Joey Tells Rachel - S8-E16
Continuity mistake: At the end of the previous episode, Joey tells Ross that he has feelings for Rachel just as Ross is about to walk out of Central Perk, and there's a vase of tulips on the table beside the door and two things hanging on the coat hooks. The opening scene of this episode continues at the same moment of Joey's admission, and the vase has vanished and there's only a sweater hanging on the coat hooks.
The One Where Joey Tells Rachel - S8-E16
Continuity mistake: When Monica and Chandler get back to the apartment Chandler tosses his coat over the back of the couch, and while they're talking about soulmates and a house of cheese we can see Chandler's coat in the reflection on the TV, but then it vanishes in the reflection, though it reappears when Chandler says that he wants to take Monica out to a restaurant.
The One Where Rachel Tells... - S8-E3
Continuity mistake: When Rachel sits down in Ross' apartment, she places her magazine down on the table with its binder facing the audience, but while Ross goes on about their one night just being fun the binder is now facing the opposite way on the table, and then it's flipped back to the original position.
Continuity mistake: When Ross introduces himself to Mona, the reception place card that Mona's holding switches from her left hand to her right hand, between shots.
The One Where the Monkey Gets Away - S1-E19
Other mistake: When Rachel's watching the soap opera on TV while babysitting Marcel, she and Marcel are sitting in the middle of the couch, but in the closeup of Dr. Francis we can see the reflection of the empty couch at the bottom of the TV screen.
The One with All the Poker - S1-E18
Continuity mistake: After the game at Ross' apartment Chandler takes Phoebe's cursed money, and when Ross wants to settle up with "the big Green poker machine who owes fifteen," Rachel's sitting down at the table in front of Ross, but then it cuts to Rachel who's suddenly standing up near the table. (00:12:30)
The One with All the Poker - S1-E18
Visible crew/equipment: After Rachel gets the call that she did not get the job, when she places the five dollar bet and asks if anyone has a problem with that, in the next wideshot as everyone says, "NO!" the reflection of moving equipment can be seen in the window behind Monica.
The One Where Heckles Dies - S2-E3
Visible crew/equipment: When Mr. Heckles is being taken away, just as the officer starts to follow the gurney the shadow of the moving boom mic can be seen on the wall behind him, at the right side of the screen. (Widescreen version).
The One Where Ross Moves In - S5-E7
Continuity mistake: When Chandler and Joey walk into the apartment to find boxes all over the place and also when Chandler talks about the air purifier, the door to the bathroom is open and the toilet is right beside the tub (odd that it's there in the first place), but when Joey tells Chandler he wants to play foosball and also when Joey's wearing the helmet, the prop toilet has vanished.
Continuity mistake: When Phoebe's driving Ross to the airport in her cab the rear view mirror vanishes from the windshield, then it reappears and disappears again. Additionally, when they start their drive the cab doesn't have a side view mirror on the passenger side, but en route the cab has acquired one, then it vanishes again.
The One With The Home Study - S10-E7
Audio problem: While the adoption social worker, Laura, is interviewing Monica and Chandler, Monica mentions to her that she's welcome to look under any of the furniture where she won't find cigarettes or porn, and then it cuts to Laura's close-up as we hear her say, "Well, actually before we look around," but her mouth is not saying those words.
The One Where Heckles Dies - S2-E3
Visible crew/equipment: Right before Monica breaks the seashell lamp there's a shot of Rachel walking into her bedroom, and just as she walks through the doorway set equipment can be seen at the right side of the screen. (Viewed on widescreen).
The One Where Heckles Dies - S2-E3
Visible crew/equipment: After Mr. Heckles is taken away, when it cuts to Phoebe walking out of the kitchen, the reflection of studio lighting array can be seen on the TV screen. Also later in Heckles' apartment, studio lighting's reflected on his TV screen.
The One Where Heckles Dies - S2-E3
Visible crew/equipment: After Monica yells "Stop with the broom, we're not making noise," when both Monica and Rachel stomp their feet the studio lighting can be seen at the top of the screen, over Ross (this doesn't refer to Monica's star light fixture). And when the others join in stomping their feet, we can also see the boom mic dip into view.
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