History Trivia / Itsalwayssunnyinphiladelphia

*** Glenn and his wife, Jill Latiano, asked fans to stop leaving comments referencing "The D.E.N.N.I.S System" on social media posts of them together, not because they find it offensive but only because the joke has been worn out due to literally dozens of people commenting it every time.

** PlayedForLaughs in "The Gang Buys a Roller Rink", where the main cast play their characters in a flashback to when they were in their early 20s (and, in Danny [=DeVito's=] case, his mid-fifties). No attempt is made to make them look younger apart from changing their hair and wardrobe, though this, of course, just adds to the joke.

** Creator/MaryElizabethEllis doesn't appear much in Season 7 and wears a loose dress in "The Gang Goes to the Jersey Shofe" to hide her pregnancy, although her bump is still noticeable.

* TheWikiRule: The [[http://itsalwayssunny.wikia.com/wiki/Its_Always_Sunny_in_Philadelphia_Wiki It's Always Sunny in Philadelphia Wiki]].

** Glenn Howerton is married to Jill Latiano, who played Kaylee the pharmacist in "The DENNIS System".

** Dee's pregnancy in Season 6 was written in because Kaitlin Olson was pregnant. The show did hide her bump before it was revealed she was pregnant in "Recap/ItsAlwaysSunnyInPhiladelphiaS06E07WhoGotDeePregnant". They actually pulled it off, though; watch "Mac and Charlie: White Trash" for some subtle hiding.
** Creator/MaryElizabethEllis doesn't appear much in Season 7 and wears a loose dress in "ItsAlwaysSunnyInPhiladelphiaS07E02TheGangGoesToTheJerseyShore" to hide her pregnancy, although her bump is still noticeable.

* ActingForTwo: Creator/GregoryScottCummins plays both Luther and his brother Donald.

*** The guys have expressed regret multiple times over accidentally giving Kaitlin an uncomfortable time onset in the early days, like when she's covered in blood late season five, and the producer spread her scenes out during the day instead of all at once, so it was solidifying on her skin.

** Dee's pregnancy in Season 6 was written in because Kaitlin Olson was pregnant. The show did hide her bump before it was revealed she was pregnant. They actually pulled it off, though; watch "Mac and Charlie: White Trash" for some subtle hiding.
** Creator/MaryElizabethEllis doesn't appear much in Season 7 and wears a loose dress to hide her pregnancy.

** Mary Elizabeth Ellis is married to Charlie Day in real life, which makes the whole RunningGag of Charlie stalking The Waitress incredible meta-irony.

** Rob [=McElhenney=]'s mother came out as a lesbian when he was eight, and two of his brothers came out as gay.

* Mary Elizabeth Ellis shows off her kickboxing skills in "The Gang Goes Bowling" when The Waitress competes in a test your strength arcade game with Dennis at the bowling alley arcade.

** The Gang as a whole seems to enjoy singing, as they'll occasionally burst into song. One early episode begins with the gang singing an ''a capella'' version of "More Than Words" by Music/{{Extreme}} for no particular reason before receiving the plot hook. It helps that all of them (save for Danny [=DeVito=], who more sing-speaks) are great singers, especially Glenn Howerton (who went to Juilliard) and Charlie Day (who grew up in a musical family).

*** Glenn and his wife, Jill Latiano, asked fans to stop leaving commenting referencing "The D.E.N.N.I.S System" on social media posts of them together, not because they find it offensive but only because the joke has been worn out due to literally dozens of people commenting it every time.

** Charlie, like his actor, can sing and play the piano. He's also great at ice skating, as Day used to play hockey.

** A story involving The Gang getting onto ''Series/FamilyFeud'' was ultimately vetoed by FX, despite the support of ''Feud'''s producers. It was later produced in Season 10 with a BlandNameProduct version of ''Feud'', complete with Creator/KeeganMichaelKey [[NoCelebritiesWereHarmed impersonating]] Steve Harvey.

* EnforcedMethodActing: The extras playing the prisoners at the end of "Mac Finds his Pride" watched Rob [=McElhenney=]'s dance performance on a projector screen, and knew only that he would be dancing and they were to applaud, but not what form his act would take. Their expressions of beatific awe are totally real.

* WhatCouldHaveBeen:
** Creator/KristenWiig was the runner-up for the role of Dee before Creator/KaitlinOlson was cast.
** Creator/AaronPaul was set to film a cameo at one point, but his filming schedule for the ''Film/NeedForSpeed'' movie prevented this. It eventually came to fruition in the sixteenth season, which reunites him with his ''Series/BreakingBad'' co-star, Creator/BryanCranston.
** According to [[https://www.reddit.com/r/IAmA/comments/1olm4y/i_am_rob_mcelhenney_ama/cct6efa/ Rob's AMA]], [[Series/{{Jackass}} Ryan Dunn]] was in talks with the cast to appear in Season 7, but he died before anything could be set in stone or filmed.
** The original pilot (without Dee) was called "It's Always Sunny on TV", based on the Music/AHa song “The Sun Always Shines on TV”. Set in Los Angeles, it featured Glenn, Rob, and Charlie [[AsHimself as struggling actors trying to pitch a TV show]] and Creator/MorenaBaccarin as [[TheOtherDarrin Carmen the trans woman]].
** In one of their early attempts to film a pilot, Rob [=McElhenney=] was focused on filming and didn't plan to appear on camera at all. Instead, the Gang had a member named [[AuthorAvatar Rob]] played by Creator/DavidHornsby (Cricket).
** One of the earliest versions of the script that would eventually evolve into the show's pilot had Rob [=McElhenney=] and Charlie Day playing washed-up adult versions of Creator/HaleyJoelOsment and Creator/FrankieMuniz, respectively. This was eventually referenced during the promotional campaign for season 8, which depicted Osment becoming TheOtherDarrin for [=McElhenney=]'s character.
** A Season 6 episode "The Gang Gets Successful" was written and filmed but went unaired. Its basic plot and scenes were adapted for the Season 7 episode "How Mac Got Fat".
** A proposed WorkingTitle for the show was ''Jerks'', among many others. Glenn Howerton has stated that somewhere he still has the list of working titles they came up during development.
** Creator/DaveBautista auditioned for the role of Luther Mc[=Donald=].
** Rob [=McElhenney=]'s first instinct when deciding on Mac's full name was Jimmy [=McDonald=]. He was only persuaded to change it to [[UnfortunateNames Ronald McDonald]] when he was told to make it more of a comedic reveal.
** The Waitress was given a name in one of the pre-series pilots. While it is no longer considered to be the character's actual name in canon, the cast ''still'' refuse to disclose what it was for the sake of maintaining the joke.
** A whole script was written for season 5 but never used. It involved a member of the ''{{Series/Jackass}}'' crew visiting the bar to [[DrowningMySorrows drown his sorrows]] while the Gang tries to perform ''Jackass''-esque pranks on him. It was suggested on the ''Sunny'' podcast that the crew might repurpose the script in the future.
** The Waiter was intended to be revealed to be the same person as the HR Director seen in "Sweet Dee Has a Heart Attack" due to both characters being played by the same actor, but this has thus far never happened.
** An idea floated for Season 15 was to have Cricket benefit heavily from the COVID pandemic. Cricket would run a successful business, and no one would know he was homeless because of virtual backgrounds and remote work.
** A cut subplot for "The Gang Replaces Dee With a Monkey" had Cricket attempting to compete with the titular monkey for the spot of Dee's replacement.

** The original pilot (without Dee) was called "It's Always Sunny on TV", based on the Music/AHa song “The Sun Always Shines on TV”. Set in Los Angeles, it featured Glenn, Rob, and Charlie [[AsHimself as struggling actors trying to pitch a TV show]] and Creator/MorenaBaccarin as [[TheOtherDarrin Carmen the transsexual]].

** Creator/AaronPaul was set to film a cameo at one point, but his filming schedule for the ''Film/NeedForSpeed'' movie prevented this. It eventually come to fruition in the sixteenth season, which reunites him with his ''Series/BreakingBad'' co-star, Creator/BryanCranston.

* UnderageCasting: Joe Polito, who plays Frank's older brother, is actually younger than Danny [=DeVito=].

** Creator/AaronPaul was set to film a cameo at one point, but his filming schedule for the ''Film/NeedForSpeed'' movie prevented this. It would eventually come to fruition in the sixteenth season, which reunites him with his ''Series/BreakingBad'' co-star, Creator/BryanCranston.
** According to [[https://www.reddit.com/r/IAmA/comments/1olm4y/i_am_rob_mcelhenney_ama/cct6efa/ Rob's AMA]], [[Series/{{Jackass}} Ryan Dunn]] was in talks with the cast to appear in season 7, but he died before anything could be set in stone or filmed.

** Creator/AaronPaul was set to film a cameo at one point, but his filming schedule for the ''Film/NeedForSpeed'' movie prevented this.

* CreatorBreakdown: Glenn Howerton left the show after Season 12 because he was starting to feel burned out creatively. He returned to act when he was told that the writers were struggling to write plots without Dennis, who is often the leader and dissenting voice among the group. He enjoyed the experience so much that he returned to the show full-time in Season 14, eventually coming back to write in Season 15 as well.

* CreatorBreakdown: Actor/writer Glenn Howerton left the show at the end of Season 12 because he was starting to feel burned out creatively. He returned to act when he was told that the writers were struggling to write plots without Dennis, who is often the leader and dissenting voice among the group. He enjoyed the experience so much he returned to the show full-time in Season 14, eventually coming back to write in Season 15 as well.