Lets get straight to the point.
8. Phoebe's knowledge of French.
Does Phoebe actually knows French. In Season 8, Phoebe didn't know the meaning of "sous." And a couple of seasons later, she is an expert in French.
7. Chandler can cry and can do it easily.
Chandler cried in Season 4, when Ross was choosing his best man. Remember just after the duck's operation. And he also cried when he proposed to Monica.
6. The Mysterious Door Lock
How could Rachel have her old key to Monica's apartment in Season 10, when the lock was changed in Season 8?
5. Joey's knowledge of Adam's apple.
Remember when Joey said that he met a girl with a big Adam's apple. Then how seasons later, he referred it to as Joey's apple?
4. The disappearance of Ben
Don't you all think that Ben was missing from the show for a really long time. I mean he is the son of the lead actor and was almost out of the picture for 4 long years.
3. The number of Tribbiani Sisters!
Remember in Season 1, when Joey said that his mother gave birth of 7 children. Well, then how can Joey have 7 sisters?
2. Rachel had kissed a girl before
Phoebe has witnessed Rachel kissing Monica. Then why was she shocked when Rachel kissed Melissa?
1. Ross is immortal
Ross was 29 years old for 3 Christmas and 3 Thanksgiving. Wow! He is just immortal. Ross remained 29 years old in Seasons 3,4 & 5.