Continuity: At the end of Series 6 when Chandler proposes to Monica her hair is brown. Then at the beginning of Series 7 (which takes up immediately where the previous episode left off) her hair is black again. Also, Rachel's hair has become much shorter.

Continuity: In the scene where Phoebe is telling Joey that his eyes "give him away" he is holding a sandwich; the camera angle cuts to behind him and the sandwich is on the table.

Continuity: Chandler is in Rachel's apartment after he has just left Monica; he says to Rachel, "You look great", then Rachel puts her hair behind her ears. The camera cuts to Chandler, then straight back to Rachel, and her hair is not behind her ears.

Other: The One with Monica's Thunder is supposed to be the same night as the previous episode which is the last episode of season six, The One with the Proposal, part 2. Yet, some major things have changed that shouldn't have. Rachel's' hair is about a foot shorter, Monica's hair is quite a bit darker, and Chandler has magically lost like 20 pounds or so.

Continuity: When Monica says "I nearly made you sleep with Ross" her hands are outstretched. The camera cuts and now they are instantly by her side.

Continuity: When Joey is asking how old he looks, his hands are in his pockets. In the next shot he is gesturing, then instantly his hands are back in his pockets.

Continuity: When Phoebe is singing for the first time, the door behind her is open or closed, depending on the shot.

Continuity: I know it's harsh, and I love the show, but gotta mention it. Series 7 begins right after the end of series 6, with the engagement celebrations continuing. However, in the few minutes that have elapsed, Chandler has somehow lost quite a bit of weight.

Continuity: Right at the start the way Rach holds the glass changes depending on the shot.

Continuity: While trying out different recipes, at one point Monica's holding a cookie in her hand. It's a whole cookie, but when the angle changes, suddenly a chunk is missing.

Continuity: In the scene when Joey is talking to the producers of Mac and Cheese, he says, "We're not even shooting them anymore?!" As he says this he lifts his left arm up, but in the very next shot his left arm is back down by his side.

Revealing: When Rachel holds up the Polaroid she took of her assistant, it appears to have been one of the actual photos taken in the earlier scene; you can see the edge of the set behind him, and the overhead lights in the black space to the right of the photo.

Revealing: In the shot of the paper with the picture of Monica and Joey, the anouncement written there starts out fine, but near the end the middle part is just repeated again.

Continuity: When 'Hums While He Pees' hands Phoebe the tickets for the ballroom dancing, they switch hands depending on the camera angle. She takes them in her right hand, but in the shot from behind she has them in her left hand.

Continuity: In the Maid Of Honour sequence, Joey's head starts to move one way. The camera cuts and it's no longer moving.

Continuity: Monica and Chandler are in their apartment talking about Monica's worries that Chandler would dump her if she put on weight. When we first see Monica, the bite mark in her apple is quite small, but a few seconds later, it is suddenley much bigger without her eating any more of it.

Deliberate "mistake": Monica sees the dog on her settee from Ross's apartment, which wouldn't be possible from the angle as Ross's place is lower than Monica's.

Continuity: At the very beginning, Joey is eating some cereal and then says he has to go to work, so puts it down on the table - but in the rest of the scene it vanishes.

Revealing: When Rachel and Tag are in the hall at the end of the episode, the tan mark from Jennifer Aniston's wedding ring is visible on her hand.

Factual error: When Monica and Chandlercome back from Ross's appartment, Chandler opens the door and Monica apears from stage left when the stairs are stage right.