* AbsenteeActor: Katherine Heigl in Season 6, by her own request. After appearing sporadically throughout the first half of the season, she was credited for six episodes she wasn't in before she finally decided she truly wasn't coming back.
* ActorAllusion: Quite a bit:
** Jo Wilson, played by Camilla Luddington, whose StarMakingRole was as [[UsefulNotes/TheBritishRoyalFamily Kate Middleton]], is referred to as "Princess" by Alex.
** In the 9th season opener, Arizona begs to keep her leg rather than have it amputated, in Series/IntoTheWest, Jessica Capshaw played Rachel Wheeler, who died on the operating table while having her leg amputated.
* TheCastShowoff: Dr. Bailey (played by former Broadway actress Chandra Wilson) sings "God Bless the Child" to her baby son in a season 3 episode. The season 7 musical episode gives almost everyone a chance to sing, but naturally the episode centers around the other Broadway veteran in the cast, Sara Ramirez (Callie).
* ContractualImmortality:
** Notably averted by Isaiah Washington, who plays Dr. Burke. Washington was fired from the set for making homophobic comments towards T.R. Knight (George O'Malley), who is gay in real life. This was worked into the script: [[spoiler:Burke leaves Cristina at the altar and doesn't even have the guts to come back to get his own things, sending his mother in his stead]].
** Season 5 ended with two characters ([[spoiler:George and Izzie]]) on the brink of death. During the summer hiatus, it became common knowledge that one of those actors ([[spoiler:George's]]) has not had their contract renewed... and sure enough, when Season 6 picked back up, that character had died.
** The previews for season 8's finale promised that one of six doctors would die in a 'plane crash. Since the actors for Meredith, Derek, Cristina, and Mark were all confirmed to have contract renewals prior, that meant only Lexie or Arizona could fit this. [[spoiler: It turned out to be the former]].
*** ZigZagged two episodes later when one of the renewed-contract characters ([[spoiler:specifically, Mark]]) checked out after only two more episodes.
* DirectedByCastMember: Kevin [=McKidd=] and Chandra Wilson have both spent time behind the camera.
* ExecutiveMeddling:
** There were originally four core interns, but producers felt that another male intern should be added. Enter Alex, who had to be both digitally added to the pilot and required new scenes to be filmed. Considering Alex is one of the most beloved characters on the show, it is an example of this trope turning out well.
** Cristina's miscarriage in Season 2 was supposed to be an abortion but was changed due to this. However, she did go through with an abortion in Season 8.
** Budget cuts for Season 9 were partly to blame for [[spoiler: the loss of three regular characters]].
* FakeAmerican: Jo Wilson is played by an English actress, while Kevin [=McKidd=] is Scottish.
** And Cristina is played by Canadian Sandra Oh.
* HideYourPregnancy: The reasoning behind Meredith's liver transplant storyline in Season Six–it was a procedure that would require a lot of bedrest for the character and to get Ellen Pompeo off her feet in real life (Shonda Rhimes has stated she was ''very'' pregnant while those episodes were being filmed).
** Also Chyler Leigh (Lexie)'s overeating during Season 5. It was a bit of an in-joke with the cast.
** Jessica Capshaw had pregnancies hidden in early season seven, late season eight/early nine, and late season twelve. For the first, her character was sent to Africa for two episodes to explain her absence.
** Sarah Drew's pregnancy was also hidden in season eight, since her character was a virgin.
** Caterina Scorsone's pregnancy will be hidden in season thirteen.
* IKnewIt: Before season 9 even aired, everyone was saying that the return of [[spoiler: Richard's wife Adele]] [[BackForTheDead would be her last]].
* NamesTheSame:
** Mark Sloan shares a name with ''another'' TV doctor, Creator/DickVanDyke's character on ''Series/DiagnosisMurder''.
** Teddy Altman: Doctor or [[ComicBook/YoungAvengers or a teenaged superhero]]. Justified as producer Allan Heinberg co-created the Young Avengers.
* {{Promoted Fan|boy}}girl: Camilla Luddington is excited to be playing Alex's LoveInterest.
* RealitySubtext: Early in the show, George is constantly asked whether he's gay. He's not, but his actor T.R. Knight is.
* WhatCouldHaveBeen: Ellen Pompeo revealed that the producers wanted to couple Meredith with Burke, and that Isaiah Washington's disappointment after this idea was scrapped contributed to off-screen tension (that eventually ended up getting him fired).
** Sandra Oh (Cristina) had played Brooke Smith (Erica)'s lesbian lover in an unrelated production, and the two mentioned that they would be comfortable with their characters hooking up.
* WordOfGod: All of the female characters are versions of or parts of Shonda Rhimes' personality, according to her.
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