Continuity mistake: Chandler, Monica and Phoebe are shown listening at the wall between their room and the room Ross is in with Charlie. However, when Ross comes into the room, the outside hallway is shown, and it is clear that the wall they were listening at actually connects to the hallway, not another room. Ross even walks in that direction when he leaves, proving it's not a dead end or similar.
Continuity mistake: In the scene where Chandler turns on music when he and Phoebe are going to "have all the sex" you see Phoebe's arm begin to move in the right corner of the screen. When it cuts to her she has not yet begun dancing, and when he goes to turn the music on again it is a duplicate clip from the initial shot.
Continuity mistake: When Ross and Chandler are talking about who broke which pact in college (the girls they agreed not to date) they are standing at the drinks table. Chandler is holding a drink in his left hand and his right hand is in his pants pocket. The shot then changes to face Ross, Chandler does not remove his hand from his pocket, but in the next shot facing him his drink is in his right hand. He then places it on the table.
Continuity mistake: When Monica's mum and dad are leaving the party, they are standing next to each other while her dad explains why he can not drive anymore. Her mum has both hands in front of her holding on to her purse, in the next shot one arm is around Monica.
Continuity mistake: When Phoebe, Chandler, Monica, and Joey are eating the organic wax, Monica has her feet up on the wall with her legs crossed left over right, but in Joey's closeups when he asks about needing a new walk, Monica's legs are crossed right over left.
Continuity mistake: After Phoebe tells Monica that she is fired from being her wedding planner, Monica says that she has never been fired. However, in "The One with Five Steaks and an Eggplant" Monica gets fired for taking the kickbacks.
Continuity mistake: In the scene where Joey and Rachel are sitting on the couch in their apartment after they decide their relationship is hopeless Rachel puts her head on Joey's shoulder. Her hair is on her face but when she lifts her head up in the very next shot her hair is now behind her right ear which she couldn't have done because her hands never left her lap.
Continuity mistake: When Monica goes to Rachel's office and invites Gavin to Rachel's birthday party Rachel gets up and goes to the door exclaiming "why did you invite him, I hate that guy." She has nothing in her hand when she gets up from her desk; but at the very end of the scene when she tells Monica to be quiet, she's got a pen in her hand for one shot.
Continuity mistake: When the girls and Mr Goodbody are talking about paying him the three hundred dollars, the top buttons of his shirt are ripped open. Half way though the scene this changes to only one button being open and his shirt looking neat and pressed, as if he had not started his strip yet.
Continuity mistake: As Rachel says "the guy hates me", in a wide shot Monica turns to her with her arms by her sides to say "does he?". It then cuts to a shot more focused on Monica where she laughs, and she's now reaching forwards to the table.
Continuity mistake: In the series nine episode with the 'hot' nanny, at the end when Rachel is on the veranda/balcony thing with Gavin, before he says 'I do have feelings for you', the shot is over the shoulder and he has his hand on the wall of the balcony, when the shot switches to the front angle his hand is by his side.
Continuity mistake: After Rachel spins the bottle and it points to Joshua, when she crawls toward him on her hands and knees the bottle is in front of her knees in the shots facing her, but in the shot facing Joshua the bottle is at her side, near her foot.
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