* ActorAllusion:
** The main characters are from the same home states as the actor playing them: Reese, like Creator/JimCaviezel, is from Washington state; Finch, like Creator/MichaelEmerson, grew up in Iowa, both Root and Creator/AmyAcker are from Texas.
** Shaw is of Persian descent, like Creator/SarahShahi, and has both a Persian and westernized first name; not to mention both has the initials [[AddedAlliterativeAppeal S.S.]] Her frequent use of football metaphors ("I know this went sideways, Finch, but you can't bench me for every mistake." "You go through identities like they're Dixie Cups, but I'm one and done?") are a reference to Sarah Shahi's former career as a Dallas Cowboys cheerleader.
** Michael Emerson saying "I've been watching you for a long time, John" sounds [[Series/{{Lost}} awfully familiar]].
** So does the sound of a receipt being printed in a taxi cab that just so happens to be driven by Michael's character. [[spoiler: LOST's sound effect for the "smoke monster" was derived from this sound.]]
--> Reese: "Where did you come from?"\\
Finch: "I breached the space/time continuum. Not really." [[Series/{{Lost}} (Yes, really).]]
** In "Witness," a student of the teacher John is protecting is reading ''The Count of Monte Cristo'' as a homework assignment. Jim Caviezel played the title count in the 2002 version of the movie.
*** Doubles as a WholePlotReference. ''The Count of Monte Cristo'' is about a man who devotes his life to revenge, heedless of the cost to others--which is a pretty fair description of [[spoiler: that episode's [=POI=], Carl Elias]].
** At one point Detective Carter tells Reese that he can't keep [[Film/ThePassionOfTheChrist playing God]].
** There are at least two scenes in "Judgement" where [[Film/ThePassionOfTheChrist Jim Caviezel]] is shown standing near [[WhatDoYouMeanItsNotSymbolic a statue of the Virgin Mary]].
** In episode 2.5 "Bury the Lede" Reese is given the alias "John Anderson." The surname "Anderson" is a derivative of [[Film/ThePassionOfTheChrist "Son of Man"]]
*** Judging from the number of [[Film/ThePassionOfTheChrist Passion Of The Christ]] references that have been made so far, it's likely that the list of Jesus jokes is only going to keep growing.
** Leon Tao just wants to get [[Series/{{Lost}} lost]].
** [[Film/DateNight This is not the first time Taraji P. Henson has played an NYPD cop investigating bent cops, chasing vigilantes]].
** In "Triggerman", Jonathan Tucker plays the POI, an Irish mobster who [[spoiler: [[TheAtoner regrets his life of crime because of love for a woman]]]]. [[Series/TheBlackDonnellys Sounds Familiar?]]
** This isn't the first time Jim Caviezel has heard someone with an English accent say [[Series/{{ThePrisoner}} "I'll be seeing you."]]
** It's also not the first time he has [[{{Frequency}} worked with a partner to use foreknowledge of violent crimes and tragic events to try to prevent them from happening.]]
** On that note, he's also sarcastically called [[{{Frequency}} "Chief" while pretending to be a cop]] in "Ghosts".
** Root [[spoiler:[[Creator/AmyAcker getting mistaken for a girl who disappeared from a library]]]]? [[Series/{{Angel}} That sounds familiar]].
** After the events of [[Main/MilestoneCelebration The Day The]] [[Recap/PersonofInterestS05E10 World Went Away]], it's not the [[Recap/AngelS05E15AHoleInTheWorld first time]] [[spoiler: Amy Acker's character gets killed off, so that she could play a god]].
** May be a coincidence but Root was initially believed to be [[spoiler: a girl who went missing from a library years earlier. Though it turned out to not be her,]] that particular backstory is not unlike another [[{{Series/Angel}} certain character]] portrayed by Creator/AmyAcker.
** Root also seems to have a thing for tasers, not unlike Fred.
** Inverted in ''Liberty''. The POI, Jack Salazar, is a member of the Navy who comes into conflict with Marines throughout the whole episode. He is played by Ray Valentin, who played Gabe Garza, a U.S. Marine, in GenerationKill.
** In ''Reasonable Doubt'', [[Creator/SarahShahi Shaw]] has to go undercover to a book club. She introduces herself as "Mindy's friend, [[Series/TheLWord Carmen]]."
** Creator/SaulRubinek plays a genius named Arthur who has ties to the U.S. government working on a secret project? [[Series/{{Warehouse13}} Hmmm...]]
* ActorSharedBackground:
** Like Jim Caviezel, Reese is from Washington state.
** Like Michael Emerson, Finch is from Iowa.
** In season 3 episode 18, ''Allegiance'', Shaw states that her mother was Iranian, making her half Iranian like Sarah Shahi, the actress portraying her. She also speaks fluent Farsi.
** Like Creator/AmyAcker, Root is originally from Texas.
*** In "QSO", Root goes undercover as a ballet dancer. We don't see what she does, but one audience member finds her quite impressive. Acker studied dance for over ten years before she was acting.
* ActingForTwo: In addition to Root, [[spoiler: [[Creator/AmyAcker Amy Acker]] also plays the physical embodiment of The Machine, which Finch hallucinates, in the [[Main/GrandFinale series finale]]. She also voices the AI, in every episode after Root's death. In the penultimate piece, in addition to the voice of The Machine, Acker also plays Root in a [[Main/ItsAWonderfulPlot world where Finch never built his creation]]]].
* TheCastShowoff: Kevin Chapman is an amateur boxer, so Fusco displays these skills on occasion.
* TheDanza:
** ''John'' Greer is played by ''John'' Nolan, though it's a moot point in that everyone uses LastNameBasis with him and the fact it's been confirmed to be an alias.
** James Hanlon as James Stills.
* ExecutiveMeddling: A positive case -- in the pilot's original script, Diane Hanson's exposure is only seen remotely. A scene was added in which Reese substitutes [[CaughtOnTape his recording]] of her talking to her dirty cops for evidence [[EngineeredPublicConfession she's presenting]] ''in court''.
** In a very significant example, the showrunners [[http://io9.com/person-of-interests-creators-had-to-fight-for-the-show-1577050140 had to fight the network to include the Machine and AI in the show at all]]. Fortunately, the executives lost that battle.
* FanCommunityNicknames: "Irrelevants."
* FanNickname:
** "Team Machine", for the main characters once they're all on the same side.
** The gun closet in Reese's apartment is known as "The Closet of Mass Destruction".
** Strictly speaking, the titular POI is Reese. The characters call the show's subjects "numbers". The fans call them [=POIs=].
** Root and Reese were dubbed "[[Anime/{{Pokemon}} Team Rocket]]" after their shenanigans in "[[Recap/PersonOfInterestS04E12 Control-Alt-Delete]]". They're also affectionately known as Murder In Laws.
** Finch is occasionally called Dadmin.
* IKnewIt: A lot of fans suspected that [[spoiler: Carter's new partner was part of HR. "Reasonable Doubt" just about confirmed that. As it turns out, Carter knew it, too!]]
* ImageSource: For SinisterSurveillance.
* InvisibleAdvertising: The amount of advertising the show gets is woefully out of proportion with how high its ratings are; it's one of the highest rated shows in the country, let alone on CBS, and yet it's rarely advertised except on the night that it airs and it's often absent from the group CBS network promotions.
** The opposite was true when the show was first introduced. CBS promotions went into overdrive during the summer of 2011 to hype the show up, with POI ads outnumbering those for fellow rookie ''Series/{{Unforgettable}}'' by about two to one. Ironically, it had the opposite effect in the ratings - the premiere dropped nearly forty percent in 18-49 from the second half of a special hourlong episode of ''Series/TheBigBangTheory'' (5.1 to 3.1), and was outrated by all but two of CBS' other Monday-Thursday dramas. Given the pedigree and heavy marketing, this was considered a disappointing start. The only upside is that the show stayed in the general vicinity of this number for its entire run on Thursdays, while several other CBS shows fell off.
** Sadly, the show was moved to Tuesdays at 10pm starting in season 3, a budding curse slot for the network which has killed almost every show placed there since ''Series/JudgingAmy'' went off the air, and is down year-to-year. Facing ''Series/SonsOfAnarchy'', one of cable's most popular series, which has grown year-to-year for three straight seasons, isn't helping. Neither is the continuation of this trope in the new slot.
* LyingCreator: Press releases initially suggested that [[spoiler:the creators killed off Elias and dropped what they'd planned for his storyline]] due to the shortened run of season five. [[spoiler:He turns up in the fifth episode of the season, alive and about as well as could be expected after being attacked by a Samaritan sniper.]]
* MeanCharacterNiceActor: True, this can be said of anyone who isn't a serial killer but plays one, but there are some notables:
** Jim Caviezel, playing an AntiHero killing machine is a devout Catholic with two young children.
** Enrico Colantoni playing affable but ruthless mob boss Elias is a spokesperson for the Tema Conter Memorial Trust, which helps first responders and such with post-traumatic stress disorder.
** Creator/RobertJohnBurke, playing the memorable and vile Patrick Simmons spent several days at Ground Zero after the September 11 attacks assisting with the search and rescue. He has since become a New York State certified firefighter. He also recently traveled to New Orleans to assist in the re-building of New Orleans fire houses.
* PlayingAgainstType: Creator/MichaelEmerson as Finch, who's almost the exact opposite of the manipulative [[Series/{{Lost}} Ben]].
** John Nolan's (who plays [[TheManBehindTheMan Greer]]) most notable movie role was [[Film/TheDarkKnightSaga George Fredericks]], a HonestCorporateExecutive and BenevolentBoss to the max. If you recognize him, it can be a little jarring to see him as a DiabolicalMastermind.
** Amy Acker who is usually cast as the moral center of most shows she's in, here very much isn't.
* PromotedFanboy: The show's [[https://www.youtube.com/watch?v=RrCkfAXrJTo [=SDCC=] 2015 sizzle reel]] is a fan-made trailer with a teaser epilogue tacked on.
* RealLifeRelative: Carrie Preston, who plays Finch's former fiance, Grace, is Creator/MichaelEmerson's [[http://www.youtube.com/watch?v=kwFKN6CKwvo&feature=g-his actual wife.]]
** James Carpinello, who plays [[Recap/PersonOfInterestS01E03 Joey Durban]], is the real life husband of [[Creator/AmyAcker Root]].
** John Nolan, who plays Greer, is the uncle of Jonathan Nolan.
** Paul Sparks (Wilson in "Relevance") is married to Annie Parisse (Kara Stanton).
** Jenna Stern (Dr. Mason in "Reassortment"), is married to Brennan Brown (Agent Donnelly).
* RetroactiveRecognition:
** [[Series/TheManInTheHighCastle Joe Blake]] shows up as the POI in the episode "[[Recap/PersonOfInterestS02E11 2-Pi-R]]".
** [[Theatre/{{Hamilton}} Aaron Burr]] is a [[ArcVillain recurring enemy]] through Season 3 ([[HilariousInHindsight while still in colonial America]]).
* ScrewedByTheNetwork: Due to falling ratings, CBS renewed the show for a shortened fifth season but gave no indication as to whether or not it would be the ''final'' season. Aside from press releases saying that production had begun and some noncommittal interviews with the cast and showrunners, there was no promotion nor any indication of when new episodes would air. It took months before the announcement that the fifth season would be broadcast at the very end of the 2015-2016 TV season, long after production wrapped, and new footage only started being released in ''April'', 2016.
** And mere hours after that announcement, CBS revealed that the fifth season would be aired on both Mondays and Tuesdays (sometimes burning off two episodes a night without advance notice) as "The Final Chapter," confirming that the season would indeed be the last one. Showrunner Jonathan Nolan tried to look at the bright side by saying that the faster release schedule would mean that the audience wouldn't have to wait as long between cliffhangers.
* ShootTheMoney: "The Day the World Went Away" (Season 5, Episode 10) would have originally cost ''four times'' the normal episode budget before significant script changes were made. Despite slashing the script, the producers felt that the bonkers car chase was absolutely necessary and went ahead with shooting it despite the significant budget overruns.
* ThrowItIn: Reese kissing Carter at the end of "The Crossing" was improvised by Jim Caviezel.
* TrollingCreator: It is a truth universally acknowledged that the POI writing team gets a sadistic pleasure out of TROLLING THE FANDOM.
* WhatMightHaveBeen: The original script for the Pilot episode revealed all of John and Jessica's backstory in that episode, and would have also included a scene where Finch provides Reese with an apartment to live in. The John/Jessica backstory was cut down and then spread out over the course of the first season, and the apartment became a birthday gift in "Many Happy Returns".
** Carter's pursuit of Reese was originally intended to continue over the course of the whole first season, but she ended up joining the team mid-way through due to [[ExecutiveMeddling pressure from CBS]].[[note]]Mileage Varies on whether or not it was a good move for her to join so soon.[[/note]]
** The showrunners have hinted perhaps jokingly, see TrollingCreator that they had planned to kill Reese before [[spoiler:Sarah Shahi's pregnancy]] changed things. Subtleties in the final storyline of the [[Recap/PersonOfInterestS04E11 relevant episode]] (namely, Reese TakingTheBullet for Finch at the end and sustaining serious damage) seem to support that.
* WhyFandomCantHaveNiceThings: The reaction to the ending of "The Crossing" has forced the show runners and [[spoiler:Taraji P. Henson]] to go into something akin to damage control mode.
-->'''Taraji P. Henson:''' "That's why people are so distraught today. And that's what art is supposed to do: [[EmotionalTorque It's supposed to make you feel]]. You're supposed to be mad and want to throw a glass and yell, "Goddammit, I'm not going to watch this show again." We did our job."
* WrittenInInfirmity: Shaw's exit from the show was due to Sarah Shahi having twins and planning to take two years off the show - the reduction of Season 5 to 13 episodes led to her reducing that leave and she appeared in nine of them.
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!!Miscellaneous Trivia:
* Jim Caviezel is ambidextrous in real life.
* Reese uses the Center-Axis Relock shooting style, first popularized in the video game Splinter Cell Conviction.
* While on location in New York City, Jim Caviezel saw some punk beating his girlfriend and "intervened", an incident which has caused some fans to come to the conclusion that he ''is'' John Reese.
** In at least one interview, Caviezel has stated that while he is not Jesus, he is in fact both John Reese and the Count of Monte Cristo.
* The (stolen) black Porsche that Reese drives in "Bury the Lede" actually belongs to Jim Caviezel.
** Which in a stroke of [[FridgeLogic Fridge]] [[CrowningMomentOfFunny Humor]], incidentally implies that John Reese stole Jim Caviezel's car.
* In the episode "[[Recap/PersonOfInterestS02E07 Critical]]", ''Series/PersonOfInterest'' became one of the first mainstream US dramas to portray a ''married'' same-sex couple.
* Kara Stanton was killed off earlier than expected because Annie Parisse is already on ''Series/TheFollowing''. Ironically, her ''Following'' character, Debra Parker, was dead by the end of that show's first season.
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