Continuity mistake: There is a scene in the guys' apartment where the phrase on the Magna Doodle keeps changing. Joey is complaining to Chandler about having to stay awake all night for a sleep study. Rachel and Ross then enter the apartment (at different times) and Ross announces he is getting married to Emily in a month. In some shots during the scene the Magna Doodle reads, "get out!" in other shots it reads, "Poop." (Widescreen).
Continuity mistake: At the end of this episode, Ross enters the door of Joey's apartment and finds Rachel and Joey kissing. Rachel says "I'm so sorry". The next episode, The One When Ross Is Fine, shows the same scene but it has been changed: Rachel never says "I'm so sorry". Joey starts talking when Ross enters the room.
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: In The One In Massapequa, Jack Gellar is eating food off a stick. When he finishes he holds the stick while Rachel asks Jack if he has any pearls of wisdom. We can see the stick over Judy's shoulder. In the next shot the stick is gone from his hand, then we see Judy put it down on a table, then it reappears in his hand, before disappearing for good.
Continuity mistake: At the start of this episode when Rachel comes in, you can see a bit of wooden floor by the door (carpet's visible in other shots). However, Monica doesn't pull up the carpet until later in the episode, after the apartment's tidier.
Continuity mistake: In the early episodes there is a wooden post in front of the door at Monica's apartment. Remember when Monica and Rachel were looking after Ben and Monica bangs his head - Ross shouts "Monica bang" and runs into it. The post doesn't appear in later series.
Continuity mistake: During an earlier episode Monica gave up her dream wedding dress so Chandler could have The Swing Kings at their wedding. So it is a little surprising that the band they actually have are called Jungle Swing.
Continuity mistake: In the scene where Phoebe asks Mike to prove that he plays piano, his arm goes from resting on the couch to on his lap from one shot to the next. After Phoebe tells him "You are really good," his left arm is resting on the couch. But in the next shot when Phoebe continues talking, his arm is resting on his lap.
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: While Monica's preparing her shake in the blender she asks Rachel about the anniversary dinner, and when Rachel tells her that she and Ross broke up, Monica throws the blender lid and it flies over the counter, but in the next shot the lid is back in Monica's hand, and then it vanishes again.
Continuity mistake: When Joey is picking up his bagel off the ground in Chandler's apartment he says something about the bagel hole being to small and he has it in his left hand. In the next shot it shows Chandler making a face and Joey's hand is empty. In the next shot Joey is sitting down and the bagel is back in his hand.
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.