History Trivia / ItsAlwaysSunnyinPhiladelphia

** Creator/KaitlinOlson and Creator/RobMcElhenney got [[RomanceOnTheSet married shortly into the run of the show]]; however, their characters of Dee and Mac have the least amount of screentime together and trade insults a little more/probably have the most vitriolic interactions than the others, with Mac even trying to strangle Dee a few times.

** The kid Frank interacts with at the water fountain in "Risk E. Rat's Pizza and Amusement Center" is played by Rob McElhenney and Kaitlin Olson's youngest son Leo.

** Creator/MaryElizabethEllis doesn't appear much in Season 7 and wears a loose dress in "The Gang Goes to the Jersey Shore" to hide her pregnancy, although her bump is still noticeable.
* IAmNotSpock: While Glenn, Rob and Charlie have fun describing their characters as like {{evil twin}}s of themselves, they do get bored of the same old memes [[note]]so no “the DENNIS system works” on pictures of Glenn and Jill, or “the Waitress lifted the restraining order” on Charlie and Mary Elizabeth[[/note]] when it involves their wives. Rob at conventions will call you out if you make bird jokes at Kaitlin.

** Charlie's sole love interest in the series is [[NoNameGiven The Waitress]]; he's a StalkerWithACrush toward her while she treats him with barely-disguised contempt at best and utter hatred at worst. They're played by Charlie Day and Mary Elizabeth Ellis, who have been HappilyMarried since 2006.
** Creator/KaitlinOlson and Creator/RobMcElhenney got [[RomanceOnTheSet married shortly into the run of the show]]; however, their characters of Dee and Mac have the least amount of screentime together and trade insults a little more than the others.

** When asked what show he would love to act on other than ''Series/BreakingBad'' [[https://www.reddit.com/r/IAmA/comments/1kaxje/comment/cbn37es/ during a Reddit AMA]], Creator/AaronPaul gave ''It's Always Sunny'' as his top answer. He would get to do so in "Celebrity Booze: The Ultimate Cash Grab".

** Creator/KaitlinOlson and Creator/RobMcElhenney got [[RomanceOnTheSet married shortly into the run of the show]], their characters of Dee and Mac have the least amount of screentime together and trade insults a little more than the others.

** Danny [=DeVito=]'s daughter Lucy has had a couple of one-shot cameos in "Mac Bangs Dennis' Mom" and "The Gang Finds a Dumpster Baby".

** Creator/KaitlinOlsen and Creator/RobMcElheney got [[RomanceOnTheSet married shortly into the run of the show]], their characters of Dee and Mac have the least amount of screentime together and trade insults a little more than the others.

** In "Mac And Charlie Write a Movie", Rob completely loses it at Charlie suggesting they make the main character's head "just one giant nose". He bows his head to hide his face but he is obviously shaking with laughter.

*** Charlie stated in no uncertain terms that he was against the network's decision to remove episodes such as "America's Next Top Paddy's Bilboard Model" from streaming and future DVD releases for their use of {{Blackface}}, believing it to be more responsible to trust that audiences could recognize that it was used in these instances to demonstrate the ignorance of the characters.

** PlayedForLaughs in "The Gang Buys a Roller Rink", where the main cast, who were in their mid-forties at the time, 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.

* AwesomeDearBoy: Creator/KaitlinOlson signed on because she thought the scripts were hilarious and enjoyed working with the main trio. Though she also made sure that [[CharacterizationMarchesOn characterization marched on]] and Dee was allowed to be as hilarious as the guys rather than just their [[StraightMan Straight Woman]].

* IronyAsSheIsCast: One aspect of Dee's character is her inability to either be funny or play a convincing character. Kaitlin Olson was a part of the legendary improv/sketch group The Groundlings before joining the show.

** Glenn Howerton has stated that, while he doesn't find the episode "Sweet Dee's Dating a Retarded Person" ''itself'' bad, he finds the title for it offensive and regrets calling it that.
** Rob [=McElhenney=] admitted that aside from "Mac Finds His Pride", the Season 13 episodes without Dennis didn't work.

* OldShame:
** Glenn Howerton has said that if there was one thing he could change about the show, it would be the title of the episode "Sweet Dee's Dating a Retarded Person," as he finds the title to be both personally offensive now and not nearly as intelligent or funny as many of the show's title gags. He, Rob, and Charlie actually address this in the podcast as it being FairForItsDay, but something that they definitely would have worked differently if the episode were made now.
** Rob has also stated that he finds the use of the slur "tranny" to describe Carmen in the early seasons [[https://www.femestella.com/its-always-sunny-philadelphia-rob-mcelhenney-regrets/ to be regrettable]].

* CopiousCreditedCreator: Creator/RobMcElheney is listed for the show as "created by" while he and Creator/GlennHowerton are listed as "developed by" and both along with Creator/CharlieDay have both Executive Producer and [[WrittenByCastmember prolific writing credits]]. [=McElheney=] and Howerton have [[DirectedByCastMember some sparse directing credits as well]].

** Rob [=McElhenney=]'s mother came out as a lesbian when he was eight, and he would spend the rest of his childhood being raised by both his dad and [[HasTwoMommies his mom and her partner]], and two of his younger brothers also came out as gay.

* GodNeverSaidThat: Since "The High School Reunion" two-parter, the theory that the Waitress' real name is Nikki Potnick based on what appeared to be a hidden BrickJoke (Frank steals a name tag with the name to break into the reunion early on into the episode and later the Waitress remarks that she wasn't able to find a name tag with her name on it when she arrived at the reunion) became incredibly popular. Since then, the cast have stated multiple times that the Waitress' name is ''not'' Nikki Potnick and that the two seemingly connected gags were unrelated (Nikki Potnick was actually an obscure CallBack to an earlier mentioned classmate of the Gang while the Waitress not getting a name tag was a riff on her status as a ForgettableCharacter) but the misconception continues to often be purported as fact.

* IAmNotSpock: While Glenn, Rob and Charlie have fun describing their characters as like {{evil twin}}s of themselves, they do get bored of the same old memes [[note]]so no “the DENNIS system works” on pictures of Glenn and Jill, or “the Waitress lifted the restraining order” on Charlie and Mary[[/note]] when it involves their wives. Rob at conventions will call you out if you make bird jokes at Kaitlin.

* MissingEpisode: "Dee Day" is the only episode in the series to not be on Hulu or on DVD. The only way to acquire it legally is via a purchase on Google.

* ThePeteBest: Jordan Reid played the role of Sweet Dee in the pilot before dropping out and being replaced by Creator/KaitlinOlson when the show was picked up for television.

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

** Rob [=McElhenney=]'s mother came out as a lesbian when he was eight, and two of his younger brothers came out as gay.
** In “Dennis and Dee Go On Welfare”, Dee pretends to be mentally disabled by wearing a bicycle helmet. Kaitlin Olson actually did suffer a skull fracture in a childhood bicycle accident.

* StuntCasting: FX executives told Rob [=McElhenney=] that they would cancel the show unless they brought on a famous actor to draw in more viewers. They eventually settled on Danny [=DeVito=]. This is one of the most successful examples of stunt casting in television history, turning a show with middling reviews and poor ratings into a critically-acclaimed show with high ratings.

* WriteWhatYouKnow: The DENNIS System, according to the creators, is a TakeThat to the pick-up artist tactics they saw in the early 2000s. Especially ''Literature/TheGame''.

** In the stage version of The Nightman Cometh, Rhea Perlman (Creator/DannyDevito's wife) plays Gladys.

* WordOfGay: [[https://www.youtube.com/watch?v=bzHPifzNh4Y According to Glenn Howerton]] talking on a Comic-Con panel, all of the main characters are "vaguely bisexual": "I don't even know if it's 'vaguely.'" He voiced a similar sentiment in an interview on ''Conan'', in which he claimed that all the characters are "a little ambiguously gay."

* WordOfGay: [[https://www.youtube.com/watch?v=bzHPifzNh4Y According to Glenn Howerton]] talking on a Comic-Con panel, all of the main characters are "vaguely bisexual": "I don't even know if it's 'vaguely.'" He voiced a similar sentiment in an interview on Conan, claiming that all the characters are "a little ambiguously gay."

* OldShame: Glenn Howerton has said that if there was one thing he could change about the show, it would be the title of the episode "Sweet Dee's Dating a Retarded Person," as he finds the title to be both personally offensive now and not nearly as intelligent or funny as many of the show's title gags. He, Rob, and Charlie actually address this in the podcast as it being FairForItsDay, but something that they definitely would have worked differently if the episode were made now.

* WordOfGay: [[https://www.youtube.com/watch?v=bzHPifzNh4Y According to Glenn Howerton]] talking on a Comic-Con panel, all of the main characters are "vaguely bisexual": "I don't even know if it's 'vaguely.'"
** He also once stated in an interview on Conan that all the characters are a little ambiguously gay, because that’s the case with most people in real life.

** 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 "Who Got Dee Pregnant". They actually pulled it off, though; watch "Mac and Charlie: White Trash" for some subtle hiding.