Friends

Because of a bet between Matthew Perry and Bruce Willis on the set of Falsas apariencias (2000) (which Perry won), Willis appeared in his three-episode guest role for free. Willis went on to win an Emmy for his guest role in Friends (1994).

The artwork in Central Perk is changed every three episodes.

Joey's statue of a white dog was originally given to Jennifer Aniston as a good luck present from her best friend when she started acting. She offered to lend it to the show for the episode where Joey became rich and bought a lot of stuff. After that episode, the producers decided to keep it.