10 Set Secrets Behind Your Favorite 'Friends' Episodes

But somehow it continues to be enjoyed by new and old fans alike. Ask anyone who's watched Friends and they'll undoubtedly have a favourite episode - but did you know the behind-the-scenes details about your favourite one?

Here are 10 set secrets behind some of the stand-out Friends episodes:

1. The One With Ross’s Wedding

According to the book Generation Friends: An Inside Look at the Show That Defined a Television Era, the iconic moment in this episode when Ross mistakenly says Rachel's name instead of Emily's was actually based on a real-life mistake made by David Schwimmer. While rehearsing lines, David accidentally said "Rachel, the taxi's here" instead of "Emily, the taxi's here". The mistake inspired producer Greg Malins and co-creator David Crane to make changes to the episode's ending, creating one of the show's biggest season-ending cliffhangers.

2. The One With The Blackout

The concept for this episode was born when NBC suggested that all of their sitcoms should have a blackout-themed episode for a whole night of programming. All shows, except Seinfeld, participated in the promotional event called "Blackout Thursday," which gave the network an upper hand on the popular Thursday night scheduling slots. Prior to this, NBC had also done a similar event called "Hurricane Saturday," featuring The Golden Girls, Empty Nest, and Nurses, all with episodes related to a tropical storm.

3. The One After The Superbowl

According to executive producer Kevin Bright, Matthew Perry invited Julia Roberts to guest star on the show by sending her a card and flowers. Julia responded by challenging Matthew to write a paper on quantum physics, saying she would agree only then. He did and faxed to her the next day. While on the show, the two reportedly flirted a lot and the writers tried to help Matthew land a date with her. They eventually dated for a short period before and after the episode aired in 1996.

4. The One In Vegas

In Season 5, specifically in this episode, there was supposedly a concept for a storyline where Chandler would cheat on Monica. Lisa Cash was brought in to portray the woman involved and mentioned that she and Matthew Perry had even rehearsed the scene together. However, Perry expressed his concerns to the writers, fearing that fans would never be able to forgive Chandler for doing so. We’re lucky that Matthew had this insight as Chandler and Monica getting their happily ever after was a fan favourite.

5. The One With The Embryos

During filming, the script would often be changed if the audience didn't react as expected, or sometimes the actors would experiment with different ways of delivering a joke to see which was most effective. The most popular episode of Friends involved the cast filming multiple takes of the trivia questions that Monica, Rachel, Chandler and Joey answered as part of a bet to win the apartment. Ultimately, the questions that got the most laughs from the live audience made it into the final cut.

6. The One With All The Thanksgivings

The turkey Monica and Joey wore on their heads in this iconic episode was not a real turkey, but a foam replica. Greg Malins, the writer, had originally wanted a real turkey for the scene, particularly to see if he could put his head in it. Unfortunately, even the biggest turkey available was not big enough to hold a human head, so Matt Le Blanc got lucky that day!

7. The One Where Paul’s The Man

Bruce Willis made a cameo appearance on the TV show Friends after losing a bet with Matthew Perry. The bet was on the success of their movie The Whole Nine Yards - Bruce was unsure about the film's performance, but Perry was confident. The terms were that if Bruce lost, he would have to make a guest appearance on Friends. After fulfilling his commitment with three episodes, Bruce generously donated his entire paycheck to charity.

8. The One Where Everyone Finds Out

While filming this episode, Phoebe had a hilarious moment when she first witnessed Monica and Chandler kissing. Matthew Perry actually inspired this scene. Lisa had a conversation with Jennifer Aniston, in which she mentioned that she had asked Matthew's permission before filming the scene. Lisa explained that she wanted to say her lines in the same way that Matthew would in real life, so she asked for his approval. Matthew, being the supportive co-star that he is, gave her the go-ahead and encouraged her, finding it amusing himself.

9. The One Where No One’s Ready

In this particular episode, there's a hilarious scene where Joey decides to wear all of Chandler's clothes while going commando. The costume was a clever illusion that made it look like he was wearing multiple layers, but in reality it was just one piece of clothing that you could step into and fasten at the back. Costume designer Debra McGuire revealed that many of the clothes on Friends were actually handmade, especially Chandler's early wardrobe, which had a vintage/retro vibe.

10. The Pilot

During the filming of the pilot episode of Friends, the network was reportedly concerned that audiences wouldn't like Monica because she slept with her boyfriend, Paul, after their first date. Lisa Kudrow recalled how they created a poll to ask viewers if they were comfortable with Monica's actions and some other similar storylines. When Friends premiered in 1994, it was considered controversial for its depiction of sex and mature themes, but compared to today's television, it seems much tamer!