* ActorAllusion: At Kaitlin's school, Marissa pretends to be an exchange student from London. Mischa Barton was born in London to British parents. OohMeAccentsSlipping also applies and is lampshaded.
* CastingGag: Tate Donovan plays Jimmy Cooper (Father to Marissa & Kaitlin) and voiced the title character in Disney's ''[[Disney/{{Hercules}} Hercules]]''. When the decision was made to finally introduce Frank Atwood (Ryan's father) in season 4, Kevin Sorbo got the role; Sorbo having played the title character in the unrelated ''Series/HerculesTheLegendaryJourneys''.
* CreatorBacklash:
** Mischa Barton publicly blamed the show for her personal issues. Shortly after the show'a cancellation, she said it was no surprise the show had been cancelled, since they killed her off.
** Tate Donovan has been rather critical of the show's younger actors in interviews following his departure from the show.
* CreatorBreakdown - Josh Schwartz was jaded by pressure from some fans and ExecutiveMeddling and seemingly zoned out during Season 3.
* DawsonCasting:
** Benjamin Mackenzie, Adam Brody, Rachel Bilson & Autumn Reeser were all in their early to mid twenties playing teenagers. Lampshaded in "The L.A."
-->'''Ryan''' (speaking of the star from the ShowWithinAShow): How does that guy play high school?\\
'''Seth''': It's ''Hollywood'', man.
** Averted with the Coopers. Mischa Barton was 17 playing 16 and Willa Holland was 14 playing 14.
* {{Defictionalization}}: Before the series, "OC" was sometimes used in print as shorthand for "Orange County," but very rarely in speech, and never prefixed with a "the." Many Orange County residents scoffed at the show's title, but over the years, some of them really do refer to the region "the OC" without irony.
* DuelingShows: With OneTreeHill. The latter lasted longer, but The OC is usually thought to be the better of the two.
* ExecutiveMeddling - Resulted in the end of the Marissa/Alex lesbian relationship. Also, apparently a big factor for the quality decline in Season 3, as Fox wanted something 'promotable' to happen every week. The writers once got a note that said, "This is Fox, not Fox Searchlight".
* FakeAmerican[=/=]FakeNationality: Kelly Rowan is Canadian.
* HeyItsThatGuy
** [[http://www.imdb.com/name/nm0828177/ Steve-O]] as an insane Marine Seth meets and drinks with in Mexico (4x02)
** [[{{House}} Thirteen]] plays Seth and Marissa's ex-girlfriend and her ex-girlfriend was [[{{Entourage}} Sloan]].
** [[{{Twilight}} Rosalie Hale]] plays one of Ryan's girlfriends and James plays the antagonist of season 3 [[spoiler: who kills Marissa]].
*** Plus Jasper romanced Kaitlin.
** Apparently when Taylor was a kid she looked like a younger version of [[ShakeItUp CeCe]].
*** And when Sandy was in college he looked like [[NewGirl Schmidt]].
** Creator/LucyHale plays Kaitlin's roommate, whose father created The Valley.
** [[Series/PrettyLittleLiars Hanna Marin]] as the AlphaBitch of Kaitlin's class and one of the girls that she bosses around is Mona Vanderwal.
** [[Series/TheVampireDiaries Vicki Donovan]] is one of Marissa's friends at Newport Union.
*** And Stefan Salvatore shot Luke.
** [[Series/TheSecretLifeOfTheAmericanTeenager Amy Juergens]] was Marissa's sister in Season 1.
** Che wound up playing [[Film/{{Moneyball}} First base for the Oakland Athetics]].
** Julie Cooper used to run a brothel on a border planet and slept with [[{{Firefly}} Malcolm Reynolds]].
** And of course [[Series/HerculesTheLegendaryJourneys Hercules]] as Ryan's father.
*** Funny thing, [[{{Disney/Hercules}} Disney's Hercules]] is Marissa's father.
** Ryan later made up for his criminal past by becoming a [[Series/{{Southland}} Police officer]]. When that didn't work, he became [[ComicBook/BatmanYearOne Batman instead]].
** [[HartOfDixie Wade]] was on the water polo team. Why does he have cornrows.
** Volchok cheated on Marissa with [[BeverlyHills90210 Naomi Clark]].
** [[GoodLuckCharlie Bob Duncan]] is Harbor's soccer coach.
* McLeaned: [[spoiler:Marissa Cooper]] was killed off at the end of season 3, as the actor wanted off the show.
* TheOtherDarrin: Kaitlin Cooper, Trey Atwood, and Theresa's mother.
** Kaitlin's Other Darrin was lampshaded when Ryan didn't recognize her after she returned.
* PlayingGertrude: Amanda Righetti was 20 playing 25 year old Hailey Nichol. This also resulted in her being younger than Adam Brody, who was playing her teenaged nephew.
* RomanceOnTheSet: Adam Brody and Rachel Bilson were engaged in real life.
* StarMakingRole: For Rachel Bilson; to a lesser degree for Benjamin [=McKenzie=] & Autumn Reeser.
* WhatCouldHaveBeen:
** Kaitlin was reintroduced in season 3 with a view to creating a spin-off following Kaitlin & her friends at boarding school. This was then retooled into keeping Kaitlin as a main cast member in the fourth season so they could keep the high school drama aspect of the show after the original group had graduated.
** The writers tried to get Trey to return in Season 4 to finish his story arc.
** In the same season, UsefulNotes/AlGore was supposed to be Summer's GEORGE recruiter, but had scheduling differences.
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