The One with the Sonogram at the End - S1-E2
Visible crew/equipment: When Ross announces that Carol's pregnant, after Chandler says, "Kind of puts that whole pillow thing in perspective..." in the next shot of Ross and Monica we can see a crew member's sleeve at the left side of the screen. (00:07:30)
The One With Ross's Tan - S10-E3
Visible crew/equipment: After Monica gets the call from Chandler about the fake car accident and leaves Phoebe with Amanda, in the next shot of Joey walking into his apartment the bulletin board that usually hangs beside the door is cut to about a quarter of its size, and it's covering part of the hole in the wall.
The One With Joey's Dirty Day - S4-E14
Visible crew/equipment: When Ross and Joey are explaining phase two of Chandler's break up (going to strip clubs), the camera switches from the girls to Ross and Joey. Behind them is Chandler and Joey's kitchen window where you can briefly see a reflection of someone passing by (crew member). At first I thought it could have been Chandler, since he was not in the scene, but after a few moments you see that Chandler has been in the bathroom the whole time. (01:35:00 - 01:39:00)
The One With Ross's Denial - S6-E3
Visible crew/equipment: After Ross tells Rachel about Warren's apartment he gives her Warren's phone number, and in the closeup while Rachel hugs Ross, and also in the following wideshots which face Ross the camera can be seen at the right side of the screen.
The One With The Stain - S8-E7
Visible crew/equipment: When Brenda is cleaning the top of the cabinets, stage lights can be seen on the top right-hand corner of the screen. (00:11:45)
The One With Chandler In A Box - S4-E8
Visible crew/equipment: When Kathy walks in while Chandler's in the box, after Phoebe tells her, "He can't talk right now," in the shot facing Kathy the end of the set wall can be seen, and there's a plastic cup with a straw sitting on a shelf off stage.
The One With Monica's Thunder - S7-E1
Visible crew/equipment: After Ross walks in with the champagne and candy bar, in the shot of Monica shouting, "I'm getting married...," on the balcony, studio lighting can be seen inside above Joey.
The One With The Proposal, part 2 - S6-E25
Visible crew/equipment: After Joey fibs and tells Chandler that Monica went to her parents, when Chandler and Joey walk into the apartment, in the shot facing the hallway we can see some of the camera equipment past the doorway, and in the next wideshot of the apartment as the camera pans to Monica the overhead studio lighting rigs can be seen at the top of the screen.
The One Where Chandler Can't Cry - S6-E14
Visible crew/equipment: While Rachel's looking out Monica and Chandler's window she tells Joey that Ross is on a date with her sister, and just as Joey comments, "I didn't know we could date your sister," a crew member can be seen moving around near the front door at the left side of the screen, and we know it's not Chandler or Monica since they're still in the bedroom wearing robes in the next shot.
The One With The Apothecary Table - S6-E11
Visible crew/equipment: When Phoebe and Rachel stop in front of the Pottery Barn window, in the first shot facing them from inside the store window the end of the brick set wall can be seen, with the camera beside it, and can also be seen when Phoebe comments that it's their exact living room.
Visible crew/equipment: When Ross notices that Ugly Naked Guy is back, in the next exterior shot we can see the top of the set as everyone gathers at the window.
The One In Barbados, part 2 - S9-E24
Visible crew/equipment: While Joey's wearing the snorkel gear he blows a grape out of his snorkel tube, and when Charlie walks into the room the opening in the wall can be seen beside the door.
The One With The Mugging - S9-E15
Visible crew/equipment: When Ross walks into Central Perk and Phoebe asks him about his class before she tells him the truth, in the closeup of Ross the camera can be seen at the right side of the screen.
The One With Rachel's Other Sister - S9-E8
Visible crew/equipment: When Monica tells Joey that he has a red plate instead of a fancy plate because it's a game, just as Joey says that he can't believe he won, we can see the camera at the right side of the screen.
The One With Ross's Inappropriate Song - S9-E7
Visible crew/equipment: While Chandler and Joey are watching Richard's videotape, when Chandler's relieved it's just football he heads off to get beer, and in the next shot as he hears the sound of moaning we can see the opening in the wall behind the TV.
The One With All The Resolutions - S5-E11
Visible crew/equipment: After his fiasco with the leather pants, powder, and lotion, when Ross is at Monica's and tells the others he's going to kiss Ben goodnight, as he starts walking to the bedroom the camera can be seen at the right side of the screen.
The One With Ross' New Girlfriend - S2-E1
Visible crew/equipment: When Rachel's at the airport and freaks out after seeing Ross with Julie, right before she steps up on the chair the grey crash mat can be seen on the floor, behind the man who's wearing white pants and is seated.
The One With Ross's Inappropriate Song - S9-E7
Visible crew/equipment: When Joey jumps on Chandler to shield him from seeing Monica's sex tape, the mat they land on is visible prior to the scene.
The One With The Baby Shower - S8-E20
Visible crew/equipment: Monica chases after Rachel's Mom to apologise and she falls over and you can clearly see the safety mat move when Monica falls on to it - it's blue and just down the first step. (00:22:00)
The One With All The Wedding Dresses - S4-E20
Visible crew/equipment: When it's Monica's turn to catch the bouquet she and Phoebe switch places, and just as Phoebe asks her if she's ready, in the wideshot studio lighting rigs can be seen at the top of the screen.
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