1. Ross and Rachel's "break" was not supposed to happen.
2. The Emily/Rachel wedding mix-up was inspired by David Schwimmer's actual mix-up of their names in rehearsal.
6. When Joey walks in wearing Chandler's clothing, it's really just cut-together pieces made to look as if they're layered, all secured with Velcro at the back.
8. Chandler and Joey's dog statue actually belonged to Aniston. She was gifted it when she got the role of Rachel.
9. The cast of Friends went to Caesar's Palace just before the show began airing as their last chance at anonymity. This is the same casino the characters visit in Season 5.
10. When Rachel undresses and sits in her lingerie on the couch waiting for Josh and then his parents come in, Joshua's dad is actually played by Perry's real-life father.
13. The scene where Phoebe sings along as Ross plays the bagpipes while the other characters try to hold in their laughter is actually a blooper that made it into the episode.
15. The theme song was originally supposed to be "Shiny Happy People" by R.E.M. They ended up going with "I'll Be There for You" by the Rembrandts, who only wrote a little snippet of it for the show — but it got so popular that they later recorded a whole version.
19. She was also apparently written out earlier than intended because Helen Baxendale wanting to focus on raising her family.
21. Aniston was already starring on the CBS show Muddling Through and was going to have to leave Friends to honor her contract on the former show — so NBC allegedly actively tried to tank the series by airing unreleased Danielle Steel made-for-TV movies at the same time as Muddling Through, hoping to steal its audience. It worked.
24. LeBlanc injured his arm in "The One Where No One's Ready," which is why Joey's arm is in a sling in the next episode.
25. "The One Where Rachel Tells Ross" originally featured a storyline where Chandler made a bomb joke at an airport, leading to him and Monica being detained, but it was cut due to 9/11.
26. And finally, although 9/11 happened as the show was airing, Friends didn't incorporate it into the storyline. Instead, the show honored New York City and its firefighters in the background of many shots, as seen below.
What's your favorite behind-the-scenes Friends fact? Let us know in the comments!
Note: Some submissions have been edited for length and/or clarity.