The One With Princess Consuela - S10-E14
Visible crew/equipment: At the very start when Monica mentions swinging, all the stage lights are visible in her glass of red wine. (00:00:20)
The One Where Joey Speaks French - S10-E13
Continuity mistake: When Joey is drinking the milk the amount in the container changes. It sometimes grows. (00:22:00)
The One With Ross's Tan - S10-E3
Continuity mistake: Ross' tan keeps changing shades. It gets lighter then darker, then lighter again. (00:12:40)
The One With The Birth Mother - S10-E9
Plot hole: David Schwimmer is 6'2" tall and Jennifer Aniston is 5'6". There is no way that clothes that fit Rachel would also fit Ross. When he puts on the clothes that Rachel bought it's obviously not Rachel's size. If it really were, it would be a lot tighter and shorter (Ross could probably wear it belly free).
The One With The Cake - S10-E4
Continuity mistake: Near the end, Monica rearranges Emma's stuffed toys in order of size. When you next see them they are jumbled up, then later they return to being neatly lined up again. (00:19:40)
The One With The Cake - S10-E4
Continuity mistake: Phoebe's robot in the toy race is behind Joey's. Joey then says unlucky and picks his toy up. Phoebe then picks hers up and it is about a metre in front of Joey's. The toy can't move that fast. (00:16:40)
Continuity mistake: When Chandler and Monica are at the hospital holding the twins right before they try and swap babies, there are two hospital tags around Chandler's left wrist which then disappear before re-appearing. (00:15:25)
Continuity mistake: When Ross and Rachel are standing at Ross' door after Rachel comes over to say goodbye and they are hugging and talking, Ross' right hand changes from being on Rachel's shoulder to on her waist and then back to her shoulder. (00:00:35)
The One After Joey And Rachel Kiss - S10-E1
Continuity mistake: At the end, Ross walks into Joey's apartment, he walks past the door. Next shot he is level with the middle of the door. (00:27:00)
The One With Princess Consuela - S10-E14
Visible crew/equipment: When Rachel announces a job in Paris, a stage light is reflected in the pot behind her. (00:20:45)
The One With Ross's Grant - S10-E6
Visible crew/equipment: When Joey turns the video off, the end of the set is visible in the TV. (00:15:10)
The One With Ross's Grant - S10-E6
Continuity mistake: When Charlie and Benjamin are at the restaurant, Benjamin says "I can't believe you chose this restaurant. You remember that night?" To which Charlie replies "I can't believe they let us back in here." However in "The One With The Fertility Test" Charlie has never been to New York before.
Continuity mistake: While Mama Joey is looking for Chick Jr. and Duck Jr., the things pinned to the bulletin board beside the door have vanished when Monica and Chandler walk in, but after Monica walks out to check on the twins everything's back up on the board like it was before.
The One Where Chandler Gets Caught - S10-E10
Continuity mistake: When Phoebe calls Chandler in the car he is not wearing the seat belt. The shot changes and suddenly he is wearing the seat belt. A second later the seat belt is off again.
The One Where Chandler Gets Caught - S10-E10
Continuity mistake: After Chandler says he loves the house, Monica says "this is huge" with her arms by her sides. We then cut to a front shot, and Monica's holding her hands in front of her. (00:04:30)
The One With Ross's Tan - S10-E3
Continuity mistake: When Ross gets a spray on tan, there is one shot where he is being sprayed in the face. Instant camera cut then it's on his chest, not near his face. (00:19:35)
The One With The Cake - S10-E4
Continuity mistake: When Ross and Rachel are driving back, Ross starts to put the seatbelt on. Instant cut, and he has his seatbelt on. (00:17:35)
Revealing mistake: When the first baby is born, Monica and Chandler are asked by the doctor if they would like to cut the umbilical cord. However, just before this line is delivered, the baby is moved and its navel is visible.
Revealing mistake: When Phoebe and Ross hit heads while in the cab on the bridge, they only just tap heads. Not enough to make them scream in pain. (00:05:15)
The One After Joey And Rachel Kiss - S10-E1
Visible crew/equipment: After the gang leaves Rachel's room, right after she asks Joey "Are they right?", if you look above Joey's head, for a split of a second you will see a boom mic. (00:09:25)
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