History Trivia / ER

* CaliforniaDoubling: Set in UsefulNotes/{{Chicago}}, filmed in UsefulNotes/LosAngeles, though they did travel to Chicago to film the exteriors.

* AbsenteeActor: Episodes that focused solely on one character usually meant that others were completely absent. Often, characters were randomly omitted with zero explanation--Susan isn't in "Hell and High Water", Kerry isn't in "Fear of Flying", etc.
* ActorAllusion:
** Creator/AlanAlda plays Dr. Gabriel Lawrence in Season 6. He became famous for playing surgeon Hawkeye Pierce in ''Series/{{MASH}}''.
** Creator/AnupamKher plays Neela's father in "Damaged". He previously played Parminder Nagra's father in ''Film/BendItLikeBeckham''.

** Lisa Zane tested for the part of Susan. She would later play one of Doug's temporary love interests.

* DirectedByCastMember: Several main or recurring cast members helmed episodes of the show. These included Anthony Edwards, Paul [=McCrane=], Laura Innes, Eriq La Salle, and Vondie Curtis-Hall. For a few of them, they continued to direct after their characters left the show.

* RealitySubtext:
** Maggie Doyle offhandedly mentions that she's a vegetarian--"No meat, no men." Her actress, Jorja Fox, is one as well, as was her character in ''Series/{{CSI}}'', Sara Sidle.
** Benton's brief, troubled relationship with Elizabeth is partly because Benton can't get over his discomfort with [[WhereDaWhiteWomenAt dating a white woman]], echoing his portrayer's sentiments--Eriq La Salle believed that having Benton date a white woman [[UnfortunateImplications played into dubious ideas]] about successful black men being "above" dating black women.

** Glenne Headly was pregnant when she played Abby Keaton Season 3, but this was disguised with surgical scrubs, having her frequently sitting or lying down and placing her behind counters or gurneys.

** Glenne Headly was pregnant when she appeared on the show, but this was disguised with surgical scrubs, having her frequently sitting or lying down and placing her behind counters or gurneys.
** Parminder Nagra was pregnant towards the end of the final season. There were attempts to disguise her bump by filming her scenes from the chest up, having her sit, wearing surgical scrubs, keeping her coat on, covering her bump with her bag or coat, or placing her behind counters or gurneys, but her bump was still visible in wide shots.

** Perhaps most notably, Mark's eldest daughter Rachel Greene was originally played by Yvonne Zima in Seasons 1-6, and then by Hallee Hirsh for the rest of the series.
** Rather egregiously, Roger [=McGrath=] (Carla Reese's husband) was played by Victor Williams in all of his appearances until Season 8, where he was suddenly played by ''Series/ChicagoHope'''s Vondie Curtis-Hall, who previously guest-starred as Carter's suicidal transgender patient in Season 1.

** Miguel Ferrer--Creator/GeorgeClooney's cousin--as a lung cancer patient in the {{Pilot}}, treated by Susan.

** Miguel Ferrer (Creator/GeorgeClooney's cousin) and Rosemary Clooney (Clooney's aunt and Ferrer's mother) both had roles in the first season, although neither interacted with Clooney on-screen.

** In 1995, Rachel Greene celebrates her sixth birthday. Assuming a birth year of 1989, by 2001 Rachel would have been twelve. Yvonne Zima, who had played Rachel up to this point and who was exactly twelve, was replaced by the then-fourteen year old Hallee Hirsh.
** Creator/KatDennings was nineteen when she played Zoe Butler, Ray's [[JailBait fourteen-year-old groupie]], in Season 12.

* DawsonCasting: In 1995, Rachel Greene celebrates her sixth birthday. Assuming a birth year of 1989, by 2001 Rachel would have been twelve. Yvonne Zima, who had played Rachel up to this point and who was exactly twelve, was replaced by the then-fourteen year old Hallee Hirsh.

* FakeAmerican: Gloria Rueben (Jeanie) is Canadian.

** Sam's son Alex was originally played by Oliver Davis in Seasons 10 and 11, but due to his commitment to the show ''Rodney'', he was played by Dominic Janes for the rest of the series.

** Rather egregiously, Roger [=McGrath=] (Carla Reese's husband) was played by Victor Williams in all of his appearances until Season 8, where he was suddenly played by ''Series/ChicagoHope'''s Vondie Curtis-Hall, who previously guest-starred in Season 1 as Carter's suicidal transgender patient.

** Neela's parents, played by Creator/AnupamKher and Kirron Kher, are married.

** Al Boulet was played by a different actor before being played by Michael Beach starting Season 2.
** Carol's mother Helen was played by different actresses.
** Sam's son Alex was originally played by Oliver Davis, but due to his commitment to the show ''Rodney'', he was replaced by Dominic Janes.
** Perhaps most notably, Rachel Greene was originally played by Yvonne Zima, and then replaced by Hallee Hirsh for the rest of the series.

* RoleEndingMisdemeanor: Lisa Nicole Carson, who plays Carla Reese (the mother of Benton's son) had concurrent roles in both ''ER'' and ''Series/AllyMcBeal''. She was fired from both for drug use, erratic behavior, as well as being in and out of mental hospitals. The ''ER'' producers were tired of her "unpleasant attitude."

** Crichton wrote the {{Pilot}} in 1974, with the intent of it being a film rather than a TV show.

* AbsenteeActor: Episodes that focused solely on one character usually meant that others were completely absent. Other times, characters were randomly omitted with zero explanation--Susan isn't in "Hell and High Water", Kerry isn't in "Fear of Flying", etc.

** Creator/AlanAlda plays Dr. Gabriel Lawrence on the show. He became famous for playing surgeon Hawkeye Pierce in ''Series/{{MASH}}''.

** Maggie Doyle offhandedly mentions that she's a vegetarian--"No meat, no men." So is her actress, Jorja Fox.

** During a surgery scene, Abby Keaton charges into the OR walking forward, pushing the door open with her hands. No surgeon would ''ever'' enter an OR like this--it would contaminate their hands.

* DirectedByCastMember: Several main or recurring cast members helmed episodes of the show. These included Anthony Edwards, Paul [=McCrane=], Laura Innes, Vondie Curtis-Hall, and Eriq La Salle. For a few of them, they continued to direct after their characters left the show.
* DuelingShows: With ''Series/ChicagoHope'', another Drama Series set at a hospital in Chicago, Illinois that happened to premiere ''one day'' before ''ER'' did. The two ended up competing directly against each other on Thursdays at 10:00 P.M. (with ''ER'' on NBC and ''Chicago Hope'' on CBS). ''ER'' ended up easily winning commercially, maintaining a place as one of the most-watched shows on television for its first 10 years, whereas ''Chicago Hope'' ended up finishing its run after sixth season. At the Emmys, the two tended to trade off, with ''ER'' being the only one of them to win the Drama Series prize, but ''Chicago Hope'' winning more often for its main cast members.

* NamesTheSame: [[Literature/JohnCarterOfMars John]] [[Film/JohnCarter Carter]], huh.

** Benton's brief, troubled relationship with Elizabeth is partly because Benton can't get over his discomfort with [[WhereDaWhiteWomenAt dating a white woman]], thus echoing his portrayer's sentiments--Eriq La Salle believed that having Benton date a white woman [[UnfortunateImplications played into dubious ideas]] about successful black men being "above" dating black women.

** Three actors from ''Film/TopGun''--Anthony Edwards (Goose/Dr. Mark Greene), Rick Rossovich (Slider/Tag), and Michael Ironside (Jester/Dr. William "Wild Willie" Swift)--appeared on the show.

** Carol was originally slated to die in the pilot, committing suicide after her break up with Doug. Julianna Margulies' performance in the pilot convinced the show-runners to have her recover and make her a regular.

** Neela mentions playing the viola in "Damaged" and "Alone in the Crowd", and she plays to her visiting parents in a deleted scene from the former. Parminder Nagra does actually play the viola.

* AbsenteeActor: Episodes that focused solely on one character usually meant that others were completely absent. Other times, characters were randomly omitted with zero explanation--Sherry Stringfield isn't in "Hell And High Water", Kerry Weaver isn't in "Fear Of Flying", etc.

** Creator/AlanAlda played Dr. Gabriel Lawrence on the show; of course, he famously played surgeon Hawkeye Pierce on ''Series/{{MASH}}''.

** Both Michael Michelle and Creator/ThandieNewton and their respective characters Cleo Finch and Kem Likasu are biracial, though the mixes are different--Michael and Thandie's fathers are white, while Cleo and Kem's mothers are.
** Maggie Doyle offhandedly mentions that she's a vegetarian--"No meat, no men". So is her actress, Jorja Fox.
** Neela tells Ray's bandmates that she plays the viola, and in a deleted scene from "Damaged", she plays to her visiting parents. Parminder Nagra does actually play the viola.

** In "Love's Labor Lost", as Mark futilely tries to revive the patient, Carol can clearly be seen taking off her glasses in the background. When the patient is pronounced dead and we get the individual reactions of everyone in the room (Susan, Carol, Lydia, Carter, Chen), Carol is seen taking off the glasses again.

* DawsonCasting: In 1995 Rachel Greene celebrates her sixth birthday. Assuming a birth year of 1989, by 2002 Rachel would have been thirteen. Yvonne Zima, who had played Rachel up to this point and who was exactly thirteen, was replaced by the then-fifteen year old Hallee Hirsh.
* DeletedScene: The [=DVDs=] featured numerous deleted scenes from various episodes, all of them unedited (certain sound effects or special effects needed to be added in post-production). Interestingly some of the scenes were subplots that were scrapped so they could be re-used or re-worked for later episodes. ''On The Beach'' had a wealth of deleted scenes, showing (amongst other things) Mark watching Ella take her first steps, Mark and Elizabeth writing his letter to the ER (as seen in ''The Letter'') and Elizabeth talking to Peter Benton at Mark's funeral.
* DevelopmentHell: The {{Pilot}} was written in 1974 and filmed 20 years later. Despite the huge time gap, few changes were necessary, aside from making at least one of the doctors (Lewis) a woman instead of a man, and another a black man (Benton) instead of a white one.
* DisabledCharacterDisabledActor: Matthew Watkins, who played Reese Benton, is deaf in RealLife.

* FakeAmerican: Gloria Rueben (Jeanie Boulet) is Canadian.
* FakeMixedRace: Inverted. Gloria Reuben is also of mixed race (black mother, biracial father). Jeanie is apparently not--we never learn much about her background, but she never mentions either parent being white.

** Miguel Ferrer--Creator/GeorgeClooney's cousin--as a lung cancer patient in the pilot, treated by Susan Lewis.

** Diane Baker--Kellie Martin's co-star in the 1998 CBS TV movie ''About Sarah''--as the daughter of a Parkinson's patient in Season 6, treated by Chen and Carter.
** James Cromwell--Anthony Edwards' co-star in ''Film/RevengeOfTheNerds''--as a bishop in four episodes of Season 7, treated by Kovač.
** Creator/GoranVisnjic worked with Clooney in ''Film/ThePeacemaker'' two years before he joined the cast as Luka Kovač following Clooney's departure.
** Julianna Marguiles and Ron Eldard had been dating for several years before he was cast as Carol's Season 2 boyfriend.
* InMemoriam: When writer Michael Crichton passed away in 2008, Eriq La Salle gave out a speech about Crichton's passing.

** Carol's mother was played by different actresses.

** Perhaps most notably Rachel Greene was originally played by Yvonne Zima, and then replaced by Hallee Hirsh for the rest of the series.

** David Brisbin, who played Alexander Babcock, is married to Laura Innes. They got to interact at least once, when Kerry is in the ICU screaming at Doug for doing a procedure in secret and without parental consent.
** Neela's parents, played by Creator/AnupamKher and Kirron Kher, are also married in real life.
** Creator/CourtneyBVance is married to Creator/AngelaBassett, who played Catherine Banfield. He plays her husband Russell.

** Benton's brief, troubled relationship with Elizabeth is partly because Benton can't get over his discomfort with [[WhereDaWhiteWomenAt dating a white woman]], thus echoing his portrayer's sentiments -- Eriq La Salle believed that having Benton date a white woman [[UnfortunateImplications played into dubious ideas]] about successful black men being "above" dating black women.
** Maggie Doyle offhandedly mentions that she's a vegetarian--"No meat, no men." Her actress, Jorja Fox, is one as well (and so was Fox's Series/{{CSI}} character, Sara Sidle).
* RoleEndingMisdemeanor: Lisa Nicole Carson, who played Carla Reese (the mother of Benton's child) had concurrent roles on both ''ER'' and ''Series/AllyMcBeal''. She was fired from both for drug use, erratic behavior as well as being in and out of mental hospitals. The ''ER'' producers in particular were tired of her 'unpleasant attitude'.

** This was true for most of the original main cast (though none of them reached the heights Clooney has). Anthony Edwards was the exception; he was fairly well-known before the show, appearing in major roles in ''Film/RevengeOfTheNerds'' and ''Film/TopGun'', even though he became the major star for several years.
** While Creator/LindaCardellini got her big break with ''Series/FreaksAndGeeks'', she has said that she became more easily recognizable after she joined this show in Season 10.

** Three actors from ''Film/TopGun''--Anthony Edwards (Goose/Dr. Mark Greene), Rick Rossovich (Slider/Dr. John "Tag" Taglieri), and Michael Ironside (Jester/Dr. William "Wild Willie" Swift)--appeared on the show.

** Crichton wrote the pilot script in 1974, with the intent of it being a film rather than a TV show.

** Julianna Margulies originally read for the part of Dr. Mark Greene's wife.
** Carol Hathaway was originally slated to die in the pilot episode, committing suicide after her break up with Doug Ross. Julianna Margulies' performance in the pilot convinced the show-runners to have her recover and make her a regular.
** Lisa Zane tested for the part of Dr. Susan Lewis. She would later play a love interest for George Clooney's character.
** Laura Innes auditioned for the role of said love interest before being cast as Kerry Weaver.

** Creator/SissySpacek was originally cast as Dr. Weaver's mother, but the role was eventually played by Frances Fisher.

* DawsonCasting: In 1995 Rachel Greene celebrates her sixth birthday. Assuming a birth year of 1989, by 2002 Rachel would have been exactly thirteen. Yvonne Zima, who had played Rachel up to this point and who was exactly thirteen, was replaced by the then-fifteen year old Hallee Hirsh.

** Parminder Nagra's pregnancy was noticeable in "Shifting Equilibrium". They tried to disguise it with having her keep her heavy coat on or covering her middle with her bag, but it was still visible in some shots.

** Hathaway's mother was played by different actresses.

** Rather egregiously, Roger [=McGrath=] (Carla Reese's husband) was played by Victor Williams in all of his appearances until the eighth season, where he was suddenly played by ''Series/ChicagoHope'''s Vondie Curtis-Hall.

** Creator/AnupamKher plays Neela's father in "Damaged". He previous played Parminder Nagra's father in ''Film/BendItLikeBeckham''.

* ActorAllusion: Creator/AlanAlda played Dr. Gabriel Lawrence on the show; of course, he famously played surgeon Hawkeye Pierce on ''Series/{{MASH}}''.

* HideYourPregnancy: Glenne Headly was pregnant when she appeared on the show, but this was disguised with surgical scrubs, having her frequently sitting or lying down and placing her behind counters or gurneys.

** Creator/CourtneyBVance (best known as [[Series/LawAndOrderCriminalIntent Ron Carver]]) is married to Creator/AngelaBassett, who played Catherine Banfield. He plays her husband Russell.

** Four actors from ''Series/LifeGoesOn''--Chad Lowe (Jesse/George Henry), Kellie Martin (Becca/Lucy Knight), Troy Evans (Artie/Frank), and Chris Burke (Corky/George)--appeared on the show at various times, though never together.
** Three actors from the film ''Film/TopGun''--Anthony Edwards (Goose/Dr. Mark Greene), Rick Rossovich (Slider/Dr. John "Tag" Taglieri), and Michael Ironside (Jester/Dr. William "Wild Willie" Swift)--appeared on the show.

* AwardCategoryFraud: Possibly to avoid canceling each other out (as possibly happened to Anthony Edwards and Creator/GeorgeClooney along with Noah Wyle and Eriq La Salle), Julianna Marguiles was nominated for Best ''Supporting'' Actress during the time when Sherry Stringfield, who was nominated for Lead, was a cast member, even though the two had roughly the same amount of screen time and storylines.

** Also counts to a lesser extent for Julianna Marguiles, Noah Wyle and Mekhi Phifer.

** The producers wanted to pair Carter and Lucy, but Noah Wyle was adamantly opposed to this, feeling that it would be out of character for Carter to pursue an inappropriate relationship--Lucy was still a medical student and therefore Carter's subordinate.

* ActorSharedBackground: Both Michael Michelle and Creator/ThandieNewton and their respective characters Cleo Finch and Kem Likasu are biracial, though the mixes are different--Michael and Thandie's fathers are white, while Cleo and Kem's mothers are.

* AwardCategoryFraud: Possibly to avoid canceling each other out (as possibly happened to Anthony Edwards and Creator/GeorgeClooney along with Noah Wyle and Eriq [=LaSalle=]), Julianna Marguiles was nominated for Best ''Supporting'' Actress during the time when Sherry Stringfield, who was nominated for Lead, was a cast member, even though the two had roughly the same amount of screen time and storylines.
* {{Blooper}}: In "Love's Labor Lost", as Mark futilely tries to revive the patient, Carol can clearly be seen taking off her glasses in the background. When the patient is pronounced dead and we get the individual reactions of everyone in the room (Susan, Carol, Lydia, Carter, Chen), Carol is seen taking off the glasses again.

* DeletedScene: The [=DVDs=] featured numerous deleted scenes from various episodes, all of them unedited (certain sound effects or special effects needed to be added in post-production). Interestingly some of the scenes were subplots that were scrapped so they could be re-used or re-worked for later episodes. ''On The Beach'' had a wealth of deleted scenes, showing (amongst other things) Mark watching Ella take her first steps, Mark and Elizabeth writing his letter to the ER (as seen in ''The Letter'') and Elizabeth talking to Peter Benton [[spoiler: at Mark's funeral]].

* IWantYouToMeetAnOldFriendOfMine: Julianna Marguiles and Ron Eldard had been dating for several years before he was cast as Carol's Season 2 boyfriend.
* InMemoriam: When writer Michael Crichton passed away in 2008, One of the cast member of the show gave out a speech about the passing of Michael Crichton.
* McLeaned: Carla Reese, see Role Ending Misdemeanour below.
* TheOtherDarrin: Several supporting characters were played by different actors. Al Boulet was played by a different actor before being played by Michael Beach starting Season Two. Hathaway's mother was played by different actresses. Perhaps most notably Rachel Greene was originally played by Yvonne Zima, and then replaced by Hallee Hirsh for the rest of the series. Rather egregiously, Roger [=McGrath=] (Carla Reese's husband) was played by Victor Williams in all of his appearances until the eighth season, where he was suddenly played by Series/ChicagoHope's Vondie Curtis-Hall.

** Creator/CourtneyBVance (probably best known nowadays as [[Series/LawAndOrderCriminalIntent Ron Carver]]) is married to Creator/AngelaBassett, who played Catherine Banfield. He plays her husband Russell.
** Miguel Ferrer (Creator/GeorgeClooney's cousin) and Rosemary Clooney (Creator/GeorgeClooney's aunt) both had roles in the first season, although neither interacted with Clooney.

** Benton's brief, troubled relationship with Elizabeth is partly because Benton can't get over his discomfort with dating a white woman, thus echoing his portrayer's sentiments - Erik La Salle believed that having Benton date a white woman played into dubious ideas about successful black men being "above" dating black women.
** Maggie Doyle offhandedly mentions that she's a vegetarian--"No meat, no men." Her actress, Jorja Fox, is one as well (and so was Fox's Series/{{CSI}} character, Sara Sidle.)
* RoleEndingMisdemeanor: Lisa Nicole Carson, who played Carla Reese (the mother of Benton's child) had concurrent roles on both ER and ''Series/AllyMcBeal''. She was fired from both for drug use, erratic behavior as well as being in and out of mental hospitals. The ER producers in particular were tired of her 'unpleasant attitude'.

** For Creator/GeorgeClooney. Also counts to a lesser extent for Julianna Marguiles, Noah Wyle and Mekhi Phifer.
** This was true for most of the original main cast (though none of them reached the heights Clooney has). Anthony Edwards was the exception; he was fairly well-known before the show (''Film/RevengeOfTheNerds'', ''Film/TopGun'') even though he became the major star for several years.
* ThoseTwoActors: Four actors from ''Series/LifeGoesOn''--Chad Lowe (Jesse/George Henry), Kellie Martin (Becca/Lucy Knight), Troy Evans (Artie/Frank), and Chris Burke (Corky/George)--appeared on the show at various times, though never together.
** Three actors from the film Film/TopGun--Anthony Edwards (Goose/Dr. Mark Greene), Rick Rossovich (Slider/Dr. John "Tag" Taglieri), and Michael Ironside (Jester/Dr. William "Wild Willie" Swift)--appeared on the show.

** Julianna Margulies originally read for the part of Dr Mark Greene's wife.
** Creator/SissySpacek was originally cast as Dr. Weaver's mother, but the role was eventually played by Frances Fisher.
** Lisa Zane tested for the part of Dr Susan Lewis. She would later play a love interest for George Clooney's character.
** Laura Innes auditioned for the role of said love interest before being cast as Kerry Weaver.

** Remember those Series/LawAndOrder and Series/HomicideLifeOnTheStreet {{Crossover}} episodes? At one point, TPTB wanted to include ''ER'', but ER's producers either declined outright or the collective group couldn't figure out how to work ER into the storyline.
** Noah Wyle was originally supposed to appear in a handful of episodes in Season 13, but this was pushed back to Season 14 (which was supposed to be the final one). However, the 2007-2008 Writers' Strike led to NBC renewing ''ER'' once again, so he ended up appearing again in Season 15 ([[BackForTheFinale along with several other cast members]]).

** Crichton wrote the pilot script with the intent of it being a film rather than a TV show.
** The show was going to be set in Boston until it was realized that this was too similar to ''Series/StElsewhere''.
* WrittenInInfirmity: The RealLife pregnancies of several of the show's actresses -- Creator/MingNaWen, Creator/AlexKingston, and Sherry Stringfield--resulted in their characters being pregnant as well.

* ActorSharedBackground: Both Michael Michelle and her character Cleo Finch are biracial, though the mix is different--Michael's father is white, while Cleo's mother is.

* HideYourPregnancy: Glenne Headly was pregnant when she appeared on the show, but this was disguised with surgical scrubs, having her frequently sitting or lying down, placing her behind counters or gurneys.

** Creator/SissySpacek was originally cast as Dr. Weaver's mother, but was eventually played by Frances Fisher.