Visible crew/equipment: While Chandler's sitting at the table waiting for the phone to ring, Joey rushes into the apartment because of telescope guy, and when Rachel walks out of her bedroom the reflection of studio lighting rigs can be seen at the top of Monica's TV screen.
Continuity mistake: When Rachel and Ross are in the apartment with Marcel, who's still wearing the pink tutu, the bottle of wine can be seen on the side table beside the teapot, but when Ross remembers the wine it's now between the teapot and the couch.
Continuity mistake: When Monica takes the newsletter from Rachel it's open to the pages with engagement news, and we can see the left page has pictures as Monica reads Mindy and Barry's notice on the right page, but when Monica wiggles out of her comment about Mindy being pretty that left page is now only words at the bottom, even though she's still open to the same page with Mindy and Barry's notice.
Visible crew/equipment: At the end, while Rachel's on the phone talking about the Visa card, in the shots facing Monica, Phoebe, Joey, and Chandler when they're playing Twister, the end of the set wall can be seen at the right side of the screen. (00:15:10)
Visible crew/equipment: After Monica tells Chandler the secret about Nancy from Phoebe's old massage place getting fired, when it cuts to the wideshot of the apartment while Rachel's standing by the fridge, we can see the camera at the left side of the screen.
Visible crew/equipment: After the anniversary party, when Rachel and Ross are back at the apartment and Ross tells her that it was the easiest four hundred bucks he ever made, Rachel gets up and just as she walks around the couch we can see the reflection of the cameraman/crew member in the mirror on the wall, at the right side of the screen.
Visible crew/equipment: After Monica whips her hair around and smacks herself in the face with all the shells in her hair, it cuts to Ross at his apartment, and the end of the set wall can be seen at the right side of the screen, with the sound stage visible. (00:21:45)
Visible crew/equipment: In Joey and Chandler's apartment, when Joey is with talking to the stripper about the duck and chicken, the edge of the set is visible where Joey's bedroom is supposed to be. The wall stops short after only a couple feet [widescreen version]. (00:09:00)
Continuity mistake: Towards the end, during a scene at Ross and Rachel's, Sandy picks up two puppets and puts them on each hand. He starts pulling the blue one onto his left hand, but when the angle changes there's a yellow one on his left hand, and a blue one on his right. It cuts to Ross, then when we go back to Sandy they've changed hands again. (00:24:30)
Continuity mistake: The gang confronts Ross over his affair with a fifty-year old librarian when he was younger. If you watch the mirror behind him (in one of the girls' rooms), it changes angles every time the camera cuts between Ross and the rest of the gang. (00:17:40)
Continuity mistake: In Central Perk, when Phoebe writes a note for Ross to put on his sandwich so no one eats it, she mentions that she stabbed a cop, and has a green mug in her hand. It cuts to Monica then back to Phoebe and the mug is out of her hand and she's yelling, "He stabbed me first." When it cuts back to the wide shot the mug is back in Phoebe's hand. (00:05:40)