1. Rachel’s birthday is May 5, 1970.
2. All the girls have kissed every friend on the show.
3. In “The One with the Stripper” Joey can be seen behind Ross laughing after Ross says, “Where’s my ring? My dead grandmother’s ring? Where is it? Where is it?”
4. In the pilot episode, Jennifer Aniston can be seen mouthing the words of the theme song during the opener.
5. Each cast member reportedly made $22,500 per episode in Season One, and gradually earned $1 million per episode in seasons 9-10.
6. In Season 3, they started to collectively bargain for their salaries, to all be paid the same. Reportedly, this meant that Jennifer Aniston and David Schwimmer took pay cuts for the sake of their co-stars.
7. Viewers never learn what the “E” in Monica’s initials, MEG stand for.
8. “Days of our Lives” the soap opera Joey is a part of in the show, is a real soap opera. In fact, Jennifer Aniston’s father, John Aniston is a long time character on “Days of our Lives.”
9. Lisa Kudrow was pregnant in real life when Phoebe was pregnant in Season 4.
10. Courtney Cox was pregnant in Season 10. She was dressed in baggy clothing to hide her bump, as Monica could not get pregnant in the show.
11. After the September 11th terrorist attacks, a scene was deleted from “The One Where Rachel Tells Ross” as it included Chandler joking about a bomb in his bag.
12. Joey’s PIN number is 5639, which spells out “JOEY” so he could remember it. He scratched it on the ATM machine by their apartment.
13. Monica’s boyfriend Pete tells Monica that soon computers will be able to recognize our voices, “So you can say ‘Wash my car.’ It won’t be able to do that, but it can understand you.’ The episode aired in 1997, years before Siri was around.
14. In “The One with the Ultimate Fighting Championship,” Billy Crystal and Robin Williams cameo in the coffee shop; The two just happened to be in the same building that day and agreed to be on the show, even though it wasn’t in the original script. The entire conversation was ad libbed.
15. Rachel lived with all of the friends except Chandler.
16. The magna-doodle on the back of Joey and Chandler’s door has a different image on it in every episode.
17. The couch in Central Perk where the friends always sit was available because of a “Reserved” sign that can be spotted in certain episodes.
18. Rachel’s grandmother’s name is Ida Green.
19. In “The One with George Stephanapoulos” the girls drink Tiki Death Punch and eat cookie dough and an incorrectly delivered mushroom, green pepper and onion pizza.
20. Chandler has a nubbin, but later Ross gets a “kundus.”
You can also read this post on Thought Catalog.