In the 40s and 50s the usual policy for films where characters would start young and get older was to cast older actors and de-age them to show them as their younger selves. "Giant" took the then largely radical step of doing the opposite - casting younger actors and using make-up to make them appear older.
In the final fist fight, note how Rock Hudson's punches are slightly louder than the diner owner's, in a subtle effort to make audiences believe that he would win the fight.
It was James Dean himself who suggested to George Stevens that Jett Rink's final drunken soliloquy should be done in longshot to emphasize the character's utter isolation.
It was the highest grossing film in Warner Bros. history until the release of Superman.
Location filming took place for two months outside the tiny Texas town of Marfa. Director George Stevens did not have a closed set but actively encouraged the townspeople to come by, either to watch the shooting, visit with the cast and crew or take part as extras, dialect coaches, bit players and stagehands.
Originally budgeted just shy of $2 million, the film ended up costing over $5 million. Despite the worries of studio head Jack L. Warner, it went on to become Warner Bros.' biggest hit up to that time.
The film has been homaged in several other movies, notably Robert Altman's Come Back to the Five and Dime, Jimmy Dean, Jimmy Dean and Kevin Reynolds' Fandango, which features a group of students making a pilgrimage to Marfa to see what remains of the ranch house set.
The film spent an entire year in the editing suites.
The film's famous final scene in which Bick Benedict battles it out with the racist owner of a diner is drastically different in Edna Ferber's novel. In that, Bick is not present, just his wife, daughter and Mexican daughter-in-law who dutifully leave without causing any trouble when told to by the diner owner.
The hat that Mercedes McCambridge wore in her exterior scenes was given to her by the wardrobe department. It was then "aged" by actor Gary Cooper so that it would look authentic. Mercedes McCambridge wrote in her memoirs that James Dean threatened to steal it.
The lead character, Jett Rink, was based upon the life of Texas oilman Glenn McCarthy (1908 - 1988). The real Glenn McCarthy was an Irish immigrant who would later be associated with a symbol of opulence in Houston, Texas: the Shamrock Hotel, which opened on St. Patrick's Day, 1949.
The massive painting seen on the set of the Benedict home is now in the Menger Hotel in San Antonio, Texas. It has hung in several spots in the original 1800s section of the hotel. It now contains a plaque, stating its significance as a film prop.
The start date of the film was delayed a few months so that Elizabeth Taylor could give birth to a son.
When Rock Hudson was cast, director George Stevens asked him whom he preferred as his leading lady, 'Grace Kelly' or Elizabeth Taylor. Hudson picked Elizabeth Taylor, who was cast in the film and ended up becoming lifelong friends with Hudson.