The One With All The Thanksgivings - S5-E8
Other mistake: When Joey comes out the bathroom in the girls' apartment with a turkey stuck on his head, the bathroom floor has the black and white tiles. But that floor wasn't there until Joey put it there in Series 3, The One With Frank Jr. So in the flashback the bathroom floor should be white tiles. (00:04:45)
Suggested correction: Joey said in the Frank Jr episode that the tiles used to be a different colour. The thanksgiving flashback was in 1992 so something must have happened to the bathroom floor tiles in the time gap between 2 years before the series started and three years after it did.
The One With Joey's Big Break - S5-E22
Other mistake: When Ross is questioning Phoebe on why she is mad at him, he has his blue sweater on backwards.
Suggested correction: So he has his sweater on backwards. That's a character mistake, not a movie mistake.