Continuity mistake: When Rachel finds out that Ross and Julie are getting a cat, watch Rachel's neck. When she says "together?" she's not wearing a necklace; cut to Ross and Julie for a fraction of a second, then when it cuts back to Rachel saying "both of you?" she's suddenly wearing a necklace. It then disappears again when she says "isn't that just lovely?" hanging off the side of the tray she's holding.
Continuity mistake: When Monica is trying to cheer Joey up, she tells him that she straightened out his shower curtain so it wouldn't get mildew. But in a previous episode (The One Where Eddie Moves In), Joey gives the gang a tour of his new apartment; the shower is clearly visible in the bathroom, and it has a door.
Continuity mistake: The prom video has just ended and the TV screen goes blank. Monica had been sitting next to Rachel, but in the reflection of the TV screen you can see her beginning to stand up. We cut back to a 'real' view, and she's sitting down; then she stands up again.
Continuity mistake: When Chandler is sitting in his kitchen with Monica and Phoebe, talking to the woman on his computer, the camera is on Monica, showing part of the computer screen. The screen is blank, indicating that the computer is off. In the next shot, the sound of an instant message is heard, indicating that the computer is in fact on.
Continuity mistake: At the beginning when Rachel falls and starts bleeding, you can see that the wound is somewhere up above her forehead because the blood is running from the wound up there. However, throughout the rest of the episode she has a bandaid going horizontally across her forehead, nowhere near where the apparent wound was.
Continuity mistake: When Paulo comes out of Rachel's bedroom to greet the group, the robe he is wearing is obviously untied and hanging open. After we see how everyone reacted to him being there, we again see Paulo but now the robe is securely tied even though neither he nor Rachel changed positions between shots.
Continuity mistake: Ross, Joey and Chandler are in Chandler and Joey's appartment talking about Ross' decision. Chandler has a green bottle in his hand. He puts it down behind the computer by the microwave, but when Ross starts listing Rachel's "cons" the bottle's suddenly at the opposite end of the counter.
Continuity mistake: Just after Rachel goes in to her surprise party in Chandler's apartment, she is talking with Ross and Chandler and says, "Both of them are here?" As she says this, she is facing forwards, yet in the next shot, she is suddenly facing Chandler.
Continuity mistake: In the scene where Monica and Ross walk in carrying a few carrier bags, Monica takes out a pack of green plates, but in the next shot she is holding 4 packs of plates - 2 green, 2 red. She did not have time to pick up another pack between shots.
Continuity mistake: When Rachel finds out that Ross and Julie are getting a cat, watch Rachel's tray. When she says "together?" she's got a towel that is flat; cut to Ross and Julie for a fraction of a second, then when it cuts back to Rachel saying "both of you?" it's now in a pyramid.
Continuity mistake: When Stephanie is singing "Angel in the Morning", there is a person in overalls sitting behind the green pole. The shot changes to Phoebe outside and you can still see the person; it changes back to Stephanie and the person is now sitting on the next table.
Continuity mistake: When 'Drake' is having dinner with Erica (the stalker), Joey is seen to be wearing a ring on the ring finger of his left hand. This can been seen just before another diner begins to choke. When the episode cuts back to them in the restaurant, the ring is gone.
Continuity mistake: When Phoebe gets the kids to sing along to 'That's another thing that you don't wanna do', there is a little boy and girl sitting perfectly still. The shot cuts to a close-up, and one of them is now standing and they are both swaying.
Continuity mistake: At the very end when U2 are on the radio it shows Rachel picking up the phone to ring the radio station. Without the song skipping it cuts to Ross and straight away the DJ comes on and says that Rachel rang her and told her what Ross did. How did Rachel ring up within the space of a second or two and say what Ross did and get the message through on to the radio?
Continuity mistake: On the actual prom video tape, it only takes Ross a mere 12-13 seconds to run up the stairs, completely change outfits into his Dad's tux, and reappear ready-to-go on the stairway. This is impossibly fast. Also, it is not possible that the prom video tape was stopped and re-started during this time, which could account for the short duration. The reason is because Ross's mom was the one filming at this point. It turns out that she has no idea how to stop the video recorder. Thus, the video tape was one continuous recording, and we are expected to believe that Ross could change outfits within 12 seconds.
Continuity mistake: When the bullies are about to fight with Chandler and Ross, they decide to put all watches and keys into a hat. He takes the hat off and places it down and everyone puts the watches and keys in. The shot changes to a further out view and the bully has a different hat on his head while another hat is still placed where he put it. When there is a closer view of him, there is once again no hat on his head.
Continuity mistake: 12 hours before the wedding, Monica asks Joey to speed it up. Here she is stirring a bowl. In the next few seconds you can see Monica holding some condiments in her hand. After Phoebe answers, Monica is stirring again and the condiments are nowhere to be seen.
Continuity mistake: In the previous episode, Joey tells Chandler that the bathroom in his new apartment has mirrors on both sides of the toilet. But in this episode, when we see the toilet from the side while Joey gives the gang a tour, it is clear that the wall is devoid of mirrors.
Continuity mistake: When Monica asks Chandler and Joey to take Richard to the Knicks, Joey tells Monica, "We will bring him, but only if he takes the Jaguar." Chandler then drops his head in mortification, and the scene then cuts to focus on Monica's expression. In the right corner of this cut, you can see Chandler is looking ahead, and his mouth is moving saying "what am I supposed to say", but there is nothing being said during this scene. The camera then cuts to a different angle where Chandler lifts his head from the earlier drop just before he speaks to Joey.
Continuity mistake: After Monica breaks the seashell lamp, when Phoebe says that she wants to believe Monica did it accidentally her right is arm up and points to Monica, but in the next shot it's Phoebe's left arm that's up while still pointing at Monica.
Add timeSuper Grover
Continuity mistake: When Joey and Chandler are at Joey's colleague's brunch, you can see a big wall clock in some shots. You can see it when Chandler says: "Wow, there's my fantasy's come true" with the minute hand at five to the hour. Just a few seconds later, when Joey says: "Can you see me in a place like this?" it can be seen when Chandler is in shot, and the minute hand is now at 20 to the hour.
Continuity mistake: When Ross gives the super the money and asks "will this help with the knob" the super says that the place isn't open until Tuesday. When he says that the money is in his right hand. Then when he asks "am I not saying it right", the money in his right hand is gone.