How I Met Your Mother premiered on CBS in the fall of 2005 and became an immediate hit. The year after Friends, cultural powerhouse filled with celebrity cameos, went off the air, the question on everyone’s lips was what show would step up and fill the void. How I Met Your Mother fit the bill: a sitcom set in New York, focused on a group of friends in their twenties, living together in different combinations, but the show became more to may viewers.

Created by Craig Thomas and Carter Bays, the pair pulled from their lives for the inspiration behind the core characters and their antics. The series stars Josh Radnor, Alyson Hannigan, Jason Segel, Cobie Smulders, and Neil Patrick Harris. Ted Mosby (Radnor) narrates the story to his children of how he met their mother, in the year 2030 as the frame, while most of the action takes place starting from 2005 onwards.

18 No Studio Audience Was Present During Filming

Though a laugh track accompanies How I Met Your Mother, the creators revealed in the series commentary the show filmed on a closed set, without audiences, because of the multiple scenes, location changes, and flashbacks. Episodes took three days to shoot, and would air for an audience, who’s laughter was recorded for the finished product.

17 Bays And Thomas Hired Based On Actors’ Work They Liked

Creator Craig Thomas and his wife Rebecca inspired the couple Marshall and Lily. She was hesitant for her husband to model a character on her, and agreed after her husband promised he’d get Alyson Hannigan for the role. The show-runners hired Jason Segel based on their love of his work on Freaks and Geeks.

16 Each Member Of The Group Has A Failed Engagement

The five main characters all have a failed engagement at some point over the series’ nine seasons: Marshall (Segel) and Lily (Hannigan) broke up before finally tying the knot; Ted (Radnor) and Stella (Sarah Chalke) in season four; Robin (Smulders) and her former therapist Kevin (Kal Penn), and finally, Barney (Harris) and Quinn (Becki Newton).

Related: 20 Celebrities We Forgot Were In How I Met Your Mother

15 The Clock In Ted And Marshall’s Apartment Is Always Set To 4:20

One thing fans loved about How I Met Your Mother was the number of running gags, and recurring bits, from Slap Bet to Robin Sparkles or the gang eating sandwiches. The sandwich joke was more present than most viewers realized, as in every episode, except season 7, episode 2, the apartment clock sits at “4:20.”

14 All The Series Stars’ Husbands Have Cameos

Three of the main cast members, Alyson Hannigan, Neil Patrick Harris, and Cobie Smulders, recruited their spouses to work on How I Met Your Mother. Hannigan’s husband, of Buffy The Vampire Slayer fame, Alexis Denisof, plays newscaster Sandy Rivers. Taran Killam, SNL alum married to Smulders, appears as lawyer Blauman. David Burtka, the husband of Neil Patrick Harris, plays Lily’s ex-boyfriend, Scooter.

13 Ted’s Children, David Henrie And Lyndsy Fonseca Filmed All Their Scenes Back In 2006, Early Into Season Two

How I Met Your Mother premiered in 2005 and didn’t know how long it would last on the air. The writers planned Victoria as the mother, were the series not renewed for a second season. In season two, Bays and Thomas filmed all the scenes with Ted’s children, played by David Henrie and Lyndsy Fonseca, as they wouldn’t stay kids forever.

12 Like Barney, Neil Patrick Harris Is A Trained Magician

How I Met Your Mother loves to pull from real life. In season 7, “The Magician’s Code: Part 1,” an airport security guard arrests Barney (Neil Patrick Harris) as he tried to sneak a magic trick out of the country. The experience happened to Neil Patrick Harris, which Carter Bays and Craig Thomas thought was hilarious.

11 Ted Dates Around 30 Women Throughout The Series

In Ted’s search for the one, he dates a lot of women over the nine seasons of How I Met Your Mother. Some of his paramours, like Victoria or Stella, last multiple episodes, whereas Mandy Moore or Rachel Bilson, drop in for cameos. Not all the women or stories were a hit.

10 Lily Is The Only Member Of The Gang To Kiss All Four Other Leads During The Series

It’s no surprise that Lily fantasizes about Robin. Often. She tries to kiss her friend anytime there’s a martini in her hand. Through the series, Alyson Hannigan is the only member of the gang to kiss all four other actors of the group: her husband Marshall, Barney, describing if he were her husband, Ted, in a flashback and Robin.

9 And All BUT Lily Have A Musical Number

Except for Alyson Hannigan, the cast is a musical bunch! Radnor sings “Super Date” in season five. Harris rules the 100th episode with, “Nothing Suits Me Like a Suit.” Smulders had a whole musical alter ego that appears throughout the series, most infamous is “Let’s Go To The Mall.” Segel sings frequently, and has a musical number “Marshall vs. the Machines.”

Related: Ranked: All Of Ted’s Relationships On How I Met Your Mother, From Worst To Best

8 Creator Cameo: Thomas And Bays Play Paramedics In A Barney Challenge

In season 1, episode 21, “Milk,” series co-creators and show-runners Craig Thomas and Carter Bays appear as fake paramedics from a local theatre company to help Barney pull off the most elaborate pick up line of the series to that point.

7 Robin Walks Down The Aisle To Sandcastles In The Sand

Robin Sparkles is an essential part of How I Met Your Mother, and other gags depend on the character. The Slap Bet stems from Robin’s secret in season two, the song “Murder Train,” from season three, and Robin even walks down the aisle to her ballad, “Sandcastles In The Sand.”

6 The Running Joke, 'Have You Met Ted?' Started When Carter And Bays Worked At Letterman

Like many gags in the series, the writers pulled from real life. Segel won a Slam Dunk Contest, Barney’s remark about how child stars were better in the 80s, reference his role as Doogie Howser. Buzzfeed revealed the infamous “Have You Met Ted” line’s origin, from the team’s time on Letterman when the host couldn’t remember Bay’s name.

5 Both Lead Actresses Were Pregnant Through Season Four

Alyson Hannigan got to sport her baby bump on the show when Lily conquers a hot dog eating contest in season five, “The Possimpible.” Most of that season, Robin (Cobie Smulders) wore billowy tops and carried large bags.

4 Friends And HIMYM Share An Actress And Joke Through Anne Dudek, Who Can’t Keep A Man On Her Birthday

Anne Dudek can’t find love in New York City. She plays the girl that Ted dumps on her birthday. Multiple times. In an episode of Friends, she played Mike’s (Paul Rudd) ex-girlfriend, Precious, who he has to break up with after returning from Barbados in season 10, episode 1.

3 A Season Six Episode Acts As A Love Letter To LOST

Jorge Garcia appears in the season six episode, “Blitzgiving.” The actor appeared in the hit ABC show LOST, and the episode contains multiple references to the show, like Garcia using the infamous numbers 4 8 15 23 42 as the random phone number his character shouts out.

Related: The Best Family Sitcoms Of All Time, Ranked

2 Robin Gave Away Her Dogs Because Josh Radnor Was Allergic

Ted describes his ideal woman as a dog lover from early episodes. The writers didn’t know until into filming that Radnor was severely allergic to dogs, which led to the season two storyline about Robin sending her dogs upstate to live with an aunt.

1 Only Four Directors Worked On The Series

Part of How I Met Your Mother’s continuity must come from so few cooks in the kitchen. Pamela Fryman directed 196 of the 208 episodes, including the series finale.  Rob Greenberg directed seven episodes, Michael Shea did four episodes, and Neil Patrick Harris made his directorial debut on an episode.

Next: 15 Behind-The-Scenes Secrets From How I Met Your Mother