I don't know if these were already noted before, but I am going to type them up anyway. I realized all 3 of them just last night.
(WARNING: Continuity Error # 3 contains a spoiler for those outside the USA.)
Continuity Error # 1
I was watching the episode TOW the Thanksgiving Flashbacks on DVD and during the episode we and the gang reminisce back to 1992 when Phoebe was still living with Monica. When Phoebe walks in to her and Monica's apartment, Joey comes in with a turkey on his head. Obviously Phoebe didn't know Joey till he moved in with Chandler. Which comes to the conclusion that how come Phoebe is still living in Monica's apartment after she had already moved out of Monica's apartment during the time Joey just moved in (which was 1993)?
Continuity Error # 2
Last night (1/11) on syndication, TOW Heckles Dies and TOW the Embryos were being shown. In TOW the Embryos Phoebe comes out of the bathroom after taking her first pregnancy test. She says then she is going to lie upside down on M/R's couch so 'gravity can do it's job." But the episode that was aired before it (TOW Heckles Dies), she specifically said she partially does not believe in gravity.
Continuity Error # 3
In last night's (1/11) episode TOW They're Up All Night, when Joey and Ross are hanging from the ladder Ross is clinging on to Joey's pants in which Joey says to Ross that he should stop holding on to them because his pants are starting to fall and he is not wearing any underwear, just like he states in TOW No One's Ready. But in the episode that aired last week (TOW All the Cheesecakes), when Joey goes into his room as Chandler is following him, Joey takes off his pants revealing he DOES wear underwear...well actually boxers.
Matt