
Continuity mistake: When Joey asks how the play was, Monica's grip on her program changes between shots. Note the gap between her hands. (00:04:20)

Continuity mistake: When Ross is reading the book he shows it to Phoebe who passes it back. Then without turning the pages he passes it to Chandler but the pages are different now. (00:07:20)

Continuity mistake: After Chandler makes the joke about Joey cracking show business, Joey is holding the phone in his left hand. In the next shot, it is in his right hand. (00:11:20)
Suggested correction: You can actually see him switch it to the other hand before the next scene pops up if you look close enough.
Not for the shot the mistake is talking about. Throughout the scene he's switching the phone back and forth. But after Chandler's line, Joey is just standing there with the phone in his left hand, he doesn't make any move to switch hands. In the next shot, the wide shot from the side showing everyone, you see the phone is in his right hand.

Continuity mistake: In the scene just before Joey goes into the shower, when he is thanking the director for the opportunity, the camera shot goes back and forth between Joey and the director several times. During this series of shots, the part in Joey's hair switches sides nearly every time. It appears that the entire shot is reversed - in the closeup, the shower curtain is on his left and the shadow to his right is sharply focused. In the lower (long) shot, the curtain is to his right, and the shadow on his left is more focused. (00:13:05)

Continuity mistake: When Chandler's partner says she's going to be late for Andrew she has her hands in front of her. Camera changes and now one hand is up by her hair. (00:18:15)

Continuity mistake: At the very end when Monica is in bed, her grip on the bed clothes changes between shots. (00:23:10)

The One with the Blackout - S1-E7
Continuity mistake: At the start of the scene where the group disclose the weirdest place they've had sex is, Monica has her hands together on her lap. In the next shot, they are underneath her legs. (00:05:30)

The One with the Blackout - S1-E7
Continuity mistake: In the scene where Joey is standing with candelight over Ross' neck, the candle is full length, but in the next shot it's only half length. (00:13:00)
The One with the Blackout - S1-E7
Continuity mistake: Rachel takes the cat to apartment number 8 and Mr. Heckles opens the door. However, in this episode, the girls' apartment is labeled number 5 which means that number 8 is above them. In later episodes, Mr. Heckles always says that the noisy girls upstairs are keeping him from doing things. [It makes a bit more sense later on in the series when Monica and Rachel's appartment changes to number 20, which is when Mr Heckles starts to complain about the noise (although in the flash back episode when Phoebe is still living with Monica it seems apparent that they actually know Mr Heckles, which Phoebe shows no sign of when she and Rachel are looking for the owner of the cat).] (00:13:40)

The One with the Blackout - S1-E7
Continuity mistake: During the Monopoly game (deleted scene), right after Monica says, "we can bring my wheelbarrow, to carry your teeth," we see Ross reading the game manual at the end of the shot. At the beginning of the very next shot, he is suddenly rolling the dice with no manual in his hands. (00:17:00)

The One with the Blackout - S1-E7
Continuity mistake: After the light comes back on and Ross is holding his heart after he sees Rachel kissing Paulo, in the next shot when Joey starts speaking to him his hand is by his side. (00:20:40)

The One with the Blackout - S1-E7
Continuity mistake: At the end of the episode, as Chandler turns to the security camera, he is stood right next to the door. In the next shot he has jumped about 2 feet away from the door instantly. (00:21:20)

The One with the Blackout - S1-E7
Continuity mistake: At the end of the episode when Chandler watches Jill leave the bank, his face is pressed up against the centre of the glass door. In the next shot his face is leaning on the metal edge around the glass. (00:21:20)
The One Where Nana Dies Twice - S1-E8
Continuity mistake: In this episode, Rachel tells Chandler that she thought he was gay until he spent Phoebe's entire birthday party talking to her breasts. But at this point since Rachel joined the group, Phoebe hasn't had a birthday yet; that occurs some episodes later, in "The One With Two Parts." (00:02:00)
The One Where Nana Dies Twice - S1-E8
Continuity mistake: When Ross and Monica are visiting Nana, Ross has his hand on Monica's shoulder. In the next shot it is gone. (00:05:05)

The One Where Nana Dies Twice - S1-E8
Continuity mistake: In Central Perk, Joey says "So, Chandler looks gay huh?" When he does his arms are not crossed. Camera cuts and they are. (00:08:30)

The One Where Nana Dies Twice - S1-E8
Continuity mistake: When Monica is talking to her dad at the table, the way he holds the magazine changes between shots. (00:08:50)

The One Where Nana Dies Twice - S1-E8
Continuity mistake: When Joey shows Chandler the TV in his pocket, at first he takes in out and is holding it in one hand. In the next shot, he is holding it in both hands. (00:14:00)

The One Where Nana Dies Twice - S1-E8
Continuity mistake: When Ross falls into the grave he ends up with a massive mud patch on his knee. He turns over and it's gone. (00:14:30)

The One Where Nana Dies Twice - S1-E8
Continuity mistake: At the funeral, Judy says to Monica that Nana would have hated this [the funeral]. When she does, Monica's arm changes position between shots. (00:18:50)