* ActorInspiredElement: Raymond was also originally written as a higher-functioning, extroverted autistic man. It was Creator/DustinHoffman who suggested making the character a more severe, introverted autistic, and they ran with it.
* BillingDisplacement: Creator/DustinHoffman gets top billing as Raymond, who is the {{Deuteragonist}}. Charlie, played by Creator/TomCruise, is the film’s true lead character.
* CastTheRunnerUp: Creator/DustinHoffman was originally hired to play the part of Charlie Babbit, but after being moved to tears seeing a savant named Leslie Lemke (who is blind, has an intellectual disability and cerebral palsy) play full concertos on the piano by ear, he decided to play the part of Raymond instead.
* DawsonCasting: Dustin Hoffman, who was 51 at the time the film was released, plays Raymond Babbitt, whose exact age is never given but is implied to be in his early 40s since he was 18 when the incident with baby Charlie happened that caused him to be institutionalized.
* DescendedCreator: Creator/JTWalsh was originally supposed to play the psychiatrist at the end of the movie. When he couldn't, Creator/BarryLevinson filled in, after Creator/DustinHoffman suggested it. Levinson said if he didn't like the way it looked, he would have someone else film it. He ad-libbed repeatedly to "push Creator/TomCruise's buttons".
* DisabledCharacterDisabledActor: [[AvertedTrope Averted]] with Creator/DustinHoffman but retroactively thankfully PlayedStraight with the extras at the group home facility where Raymond resides who have actual developmental disabilities.
* DuelingMovies: With ''Film/Twins1988''.
* MethodActing: Creator/DustinHoffman's portrayal of Raymond changed so much over the course of making the film that by the time the second half was filmed, they had to re-film the first half because Hoffman's portrayal had improved so much. Hoffman worked with Kim Peek for a while to try and understand him. Hoffman later suggested they let Kim interact with the public more via forums as he saw a big improvement with his social skills after only a few days of interacting with a stranger. Kim (with his father and caretaker) started doing conventions and because of this movie he was in high demand and very popular.
* RealLifeRelative: Creator/DustinHoffman's son Jake is the boy at the pancake counter.
* TheRedStapler: Creator/TomCruise's wearing Ray Bans boosted sales of that style 15%.
* SerendipityWritesThePlot: The script originally called for two farm kids, but after Catherine Dougherty brought six of her seven sons to audition for the part, the script was re-written to include the six boys. The boys also have an older brother and one younger sister.
* ThrowItIn:
** On ''Oprah'', Creator/TomCruise and Creator/DustinHoffman said the "farting in the phone booth" bit was improvised when Hoffman actually passed gas while the scene was being filmed. Hoffman said it was his favorite scene ever.
** Creator/BarryLevinson was persuaded to take the role of the psychiatrist in the climactic scene after the actor who had been cast didn't show.
* WhatCouldHaveBeen:
** The script was originally written with real-life brothers Creator/RandyQuaid and Creator/DennisQuaid in mind.
** Creator/DustinHoffman originally wanted Creator/BillMurray to play Charlie.
** Creator/RobertDeNiro, Creator/LiamNeeson and Creator/JackNicholson turned down the part of Raymond.
** Creator/MegRyan turned down the role of Susanna.
** Creator/MartinBrest was originally going to direct, but abruptly bailed when production was due to start due to "creative differences". Creator/StevenSpielberg stepped in but left after a few months to work on ''Film/IndianaJonesAndTheLastCrusade''. Creator/SydneyPollack was then hired, but he eventually left as well, leaving the project without a director until Creator/BarryLevinson signed on. Spielberg gave his notes to Levinson.
** The part of Susanna had originally been written as a [[WhiteAngloSaxonProtestant WASPish]] blonde woman. By having a foreigner (Italian actress Creator/ValeriaGolino) whose native tongue wasn't English play the role, it allowed for Tom Cruise's character to do a lot of exposition.
* WriteWhatYouKnow: Writer Barry Marrow based Raymond on a real life autistic man he met. He admits that he took the man away from the institute and took him on a road trip.
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