1. before settling on "Friends" ,other titles producers considered were Friends Like Us, Six Of One, Across The Hall, and Insomnia Cafe.
2. Originally, the show focused on four characters: Monica, Ross, Rachel, and Joey. Phoebe and Chandler were going to be supporting characters.
3. Season 2 is the only season without Thanksgiving episode.
4. Monica and Joey were originally intended to be main couples on the show.
5. Ellen Degeneres turned down the role of Phoebe.
6. in reality, Joey's white dog statue belonged to Jennifer Aniston, it had been given to her by a friend as a good-luck gift.
7. Bruce Willis guest starred on the show for free.
P.S. More fact here.