The One With Ross's Library Book - S7-E7
Factual error: When Ross shows Chandler the book, he claims it is in "the biggest library on campus" at NYU, which would be Bobst library on Washington Square Park South. Later, in Central Perk, when Ross tells Rachel and Joey about the people "making babies" in front of his book, Joey says, "Wait a minute. Fifth floor, against that back wall?" Bobst's fifth floor is conference rooms only; there are no stacks on that floor. Joey might have been confused, but Ross should know better, being a professor and having just visited that location. (00:08:30)
The One With Phoebe's Cookies - S7-E3
Continuity mistake: When Chandler and Jack are placing their robes on the hook, they change positions when Jack looks at Chandler naked. (00:19:39 - 00:20:08)
The One Where They All Turn Thirty - S7-E14
Continuity mistake: In The One Where They All Turn Thirty, it is Rachel's birthday. They show flashbacks of all the other Friends' thirtieth birthdays despite Monica's birthday supposedly being months after Rachel's. Plus, earlier on in the show Joey was 25 when Monica was 26, and since Monica and Rachel were in the same grade Joey should actually be a year younger than them, not a year older.
The One With All The Cheesecakes - S7-E11
Continuity mistake: When Ross and Monica are at the wedding reception talking to the other guests at their table, a lady wearing a red scarf is standing behind them with her back turned. Throughout the scene the red scarf keeps changing position very quickly - in one shot it's slid down one shoulder, then back up in the next and then slid down again. At the end of the scene it's off her back entirely and she has just slung it over her arms. (00:12:15 - 00:13:15)
The One With Ross's Library Book - S7-E7
Continuity mistake: When Phoebe is eating the muffin, it has no white paste on it. Then the shot changes and there's a line of white paste.
The One With Ross's Library Book - S7-E7
Continuity mistake: After Monica tells Chandler that they are going to have lunch with Janice, it shows Central Perk. The people in the window are different when the shot changes.
The One With Ross's Library Book - S7-E7
Continuity mistake: When Rachel asks Ross what's wrong, her hand is up. Shot changes and it's down.
The One With Ross's Library Book - S7-E7
Continuity mistake: When Janice sees Monica's ring, she's wiping her hands with a rag, then it disappears. (00:03:50)
The One Where Chandler Doesn't Like Dogs - S7-E8
Visible crew/equipment: When Chandler sees the empty dog basket on the floor at Ross' there is a panning shot to the door. If you look carefully, you can see a crewmember wearing blue jeans and white shoes. (00:17:25)
The One With Rachel's Big Kiss - S7-E20
Other mistake: Matthew Perry supposedly really likes wearing a tux that turns out to have been made for Diane Keaton. Except that Diane Keaton is 5'7" and Matthew Perry is 6 feet tall, and also considerably larger than the very slim Diane. He wouldn't even be able to put it on.
The One With Phoebe's Cookies - S7-E3
Character mistake: When Phoebe brings in her frozen cookie and Monica tastes it to try to determine the ingredients, she says "I definitely taste nutmeg." She then goes on to brag about how that's the difference between a professional and a layman. Except that later when she finds the actual recipe, it's from the Nestle Toll House bag - and that contains no nutmeg.
The One With Monica and Chandler's Wedding, Part 1 - S7-E23
Continuity mistake: When Monica and Chandler walk toward the middle of the room the camera cuts to Ross talking to his parents saying that he could kick Chandler's ass, Behind them are Monica and Chandler in a different place, listening and laughing to Ross. (00:10:50)
Suggested correction: The shot is continuous. There is no continuity mistake.
The One With All The Cheesecakes - S7-E11
Continuity mistake: When Rachel and Chandler are out in the hall eating cheesecake off the floor, Chandler's piece is much closer to Rachel's piece than in the previous scene when Rachel slapped it out of Chandler's hand closer to the apartment doorway.
The One Where They're Up All Night - S7-E12
Visible crew/equipment: Right after Tag wonders if he can see his apartment from there, when Ross says "wow, look at all the stars" a boom-mic is visible for a short amount of time.
The One With Ross's Library Book - S7-E7
Visible crew/equipment: When Chandler puts a plate down next to the Chinese food, and Monica walks in a boom mic can be seen over her head. (best on DVD). (00:06:20)
The One With All The Cheesecakes - S7-E11
Continuity mistake: In the scene when Phoebe says goodbye to David, you can see Phoebe's long hair on her back. The scene goes back and forth between Phoebe and David or Phoebe and Joey (after David leaves). Each time the amount of hair on Phoebe's back changes. Sometimes it is a thin bit of hair, other times a large chunk (while the rest of her hair is framing her face in front). (00:19:10)
The One With Ross and Monica's Cousin - S7-E19
Continuity mistake: When Cassie shows Ross her freckles on her shoulder, her hand positioning changes between shots.