The group shared many memories from the series including cast crushes and injuries – and even revealed what they didn’t like about the show.
Here are some of the biggest moments and revelations from the special that we absolutely loved.
WARNING: Spoilers ahead
Ross and Rachael were almost a thing in real life
While their characters Ross and Rachel were involved in a high-profile love story, fans may not have known the actors who played them actually had a crush on each other at one point.
We can’t believe this is the first we’re hearing of this.
“The first season I had a major crush on Jen,” Schwimmer revealed.
“And I think we both, at some point, were crushing hard on each other but it was like two ships passing because one of us was always in a relationship and we never crossed that boundary. We respected that.”
Aniston agreed and confirmed their first kiss came on screen when Ross and Rachel embraced at the Central Perk coffee house in season 2, episode 7.
She said: “So we just channelled all of our adoration and love for each other into Ross and Rachel.”
What could have been, eh?
Casting for the show was a nightmare
Although the casting choices seemed perfect for the show, Marta Kauffman and her co-creators David Crane and Kevin S. Bright went through a lot to get the right people.
“We saw approximately a gazillion people!” said Kauffman.
Schwimmer had quit TV but they begged him to join the show and sent gift baskets. They must have been some pretty nice gift baskets.
Both Perry and Aniston faced an obstacle too, with both of them already signed to other shows.
Aniston asked to be released and that show’s producer told her that Friends would “never make her a star”. The joke is definitely on them.
LeBlanc was up against one other actor - who funnily enough returned in one episode as Fake Joey. The actor– who had just $11 in his pocket at his audition – also turned up to the audition with scab on his nose from a drunken mishap with a toilet.
Matt LeBlanc dislocated his shoulder during filming
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 in an argument over a chair.
But during the special it was revealed the episode also resulted in an injury for one of the cast members.
LeBlanc was required to jump onto the furniture as part of the script.
The first three attempts went “perfectly,” producers said, but the fourth resulted in LeBlanc dislocating his shoulder.
Talk about commitment to the role.
The incident was shown during the special.
Funnily enough, this happened when LeBlanc missed the traditional huddle before filming. We’re not superstitious, but it is strange coincidence...
Phoebe and Lady Gaga perform a duet
The star-studded special saw one of the world’s biggest pop singers performing alongside a cast member.
Kudrow, in character as Phoebe Buffay, 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.
We all know from the show that Phoebe is definitely more of a solo artist.
Ross did not like Marcel
Despite a budding bromance between Ross and monkey Marcel on screen during show’s early seasons, it appears that this wasn’t the case in reality.
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.
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.
He said: “I would have monkey grubby hands all over. It was time for Marcel to f*** off!”
We can see why Marcel wasn’t invited to the reunion...
Celebrities love Friends as much as we do
Lady Gaga was not the only famous cameo to feature in the reunion.
Justin Bieber joined in on the fun when he perfected his catwalk strut dressed in Ross’ Spudnik costume from season eight episode titled, The One With The Halloween Party.
Speaking of catwalks, Cindy Crawford made an appearance wearing Ross’ iconic leather pants that he just couldn’t get off in the season five episode, The One With All The Resolutions.
David Beckham also revealed which character from the show he relates to the most - "I would have to say I’m most like Monica because I’m a clean freak!”
The audience played a key role in Monica and Chandler’s romance
At the end of Friends, 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 Monica and Chandler had spent the night together convinced them to pursue the storyline, rather than leave it a one-off.
Kaufman said: “It was such a powerful moment that we knew we had to explore it more.”
Can you imagine what would’ve happened if the audience had a different reaction?
Cameos from old favourites
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 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.
Watch Friends: The Reunion on Sky One and streaming service NOW.