Thereunion special revealed secrets about the show even die-hard fans may not have known.
The cast — Courteney Cox, Lisa Kudrow, Jennifer Aniston, David Schwimmer, Matt LeBlanc and Matthew Perry — reminisced about their time together and pulled the curtain back on a TV juggernaut.
Here are some of the biggest moments from the special:
Life almost imitated art for Jennifer Aniston and David Schwimmer. While their characters Ross and Rachel were involved in a high-profile love story, fans may not have known that the actors who played them almost followed in their footsteps.
"The first season I had a major crush on Jen," Schwimmer revealed.
Aniston agreed and confirmed their first kiss came on screen when Ross and Rachel embraced at the Central Perk coffee house.
Season three's 'The One Where No One's Ready' is best known for the moment Joey enters the room wearing all of Chandler's clothes.
But during the special, it was revealed that the episode also resulted in an injury for one of the cast members.
It included a storyline of Chandler and Joey arguing over a chair and required LeBlanc to jump onto the furniture. The first three attempts went "perfectly," producers said, but the fourth resulted in LeBlanc dislocating his shoulder. The incident was shown during the special.
The star-studded special saw one of the world's biggest pop singers performing alongside a cast member.
Kudrow, in character as Phoebe, was seated on the Central Perk sofa, guitar in hand, for a rendition of her famous song 'Smelly Cat'. She was soon joined by Lady Gaga for a duet, before later being accompanied by gospel singers.
"Still think it's better when it's just me," Kudrow muttered.
During a Q&A segment, the stars were asked if there was a part of the show they did not like.
"The monkey," Schwimmer replied, meaning Marcel, Ross's pet from the early seasons.
He revealed the animal would frequently mess up the cast's carefully choreographed moves, leaving otherwise perfect takes on the cutting room floor. And worse, according to Schwimmer, Marcel's handler would feed him live bugs, which he would then eat and wipe his hands on the actor.
At the end of, Monica and Chandler, happily married and having started a family, were moving out of New York City to embark on the next stage of their lives together.
However, that was not the original plan.
Producers revealed the "insane" reaction of the studio audience when it was first revealed that Monica and Chandler had spent the night together convinced them to pursue the storyline, rather than leave it a one-off.
co-creator Marta Kaufman said: "It was such a powerful moment that we knew we had to explore it more."
Fans will be delighted to know some of the show's best-loved supporting characters returned for the special.
They included Larry Hankin, who played noisy neighbour Mr Heckles. The barbershop quartet used by Ross to deliver a message to Rachel congratulating her on her new job also made an appearance.
Joey's hand twin, played by Thomas Lennon, turned up to embrace LeBlanc while Tom Selleck, who starred as Monica's older boyfriend, Richard, also surprised the cast.
There was an emotional moment when Elliott Gould and Christina Pickles — who played the Gellers' parents — turned up in the studio audience.
And Maggie Wheeler — also known as Janice — appeared and performed her catchphrase "Oh! My! God!" while James Michael Tyler, who played Gunther, the coffee shop manager in love with Rachel, Zoomed in.
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