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.
Plot hole: In the beginning the Friends enter Central Perk and see that there are some other people on their couch. Monica looks fine and happy - even though later in the episode the other Friends say that she's been depressed for some days now, and she doesn't leave her apartment.
Character mistake: In one of the scenes where Phoebe is teaching Joey guitar, she asks him to demonstrate the "Iceberg" chord. To refresh his memory, Joey refers to the chord as "G Sharp." In reality, the only way to play a G Sharp chord is with a barre chord, and as such the fingering is not exclusive to it.
Add timeDaniel Knight
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.