After the mixed reception to Indiana Jones and the Temple of Doom, Spielberg deliberately aimed to make a more lighthearted film that recaptured the tone of Raiders of the Lost Ark, describing himself as 'consciously regressing' during development.

Because of his commitment to directing this film, Spielberg had to drop out of directing both Big and Rain Man.

Early story ideas included a 'haunted mansion movie' script by Diane Thomas (rejected for resembling Poltergeist) and a Lucas treatment called Indiana Jones and the Monkey King, later developed by Chris Columbus into scripts involving a Garden of Immortal Peaches, a resurrection by a Monkey King, and a mechanical-armed Nazi named Sergeant Gutterbuhg; this direction was abandoned partly over concerns about its negative depiction of African natives.

A leaked 1997 draft of Chris Columbus's script was mistakenly believed by many to be an early version of the fourth Indiana Jones film because it had been mis-dated to 1995.

Writer Jeffrey Boam proposed having Indiana find his father in the middle of the story rather than at the end, arguing the father-son relationship, not the Grail quest itself, should be the emotional core of the film.

Tom Stoppard did an uncredited rewrite of the script under the pseudonym 'Barry Watson,' polishing dialogue and creating the 'Panama Hat' character to connect the prologue's two time periods.

Sean Connery initially turned down the role of Henry Jones Sr. because he was only twelve years older than Harrison Ford and had avoided franchise films since James Bond, but he eventually relented and reshaped the character, comparing him to Richard Francis Burton.

Connery improvised the line 'She talks in her sleep,' revealing that he too had slept with Elsa, and the ad-libbed moment was kept in the film because it made everyone on set laugh.

Harrison Ford recommended River Phoenix to play young Indiana Jones, having previously played his son in The Mosquito Coast, and felt Phoenix most resembled how Ford looked at that age.

Laurence Olivier was originally considered to play the Grail Knight but was too ill to take the role and died the same year the film was released.

Alison Doody was only 21 when she auditioned to play the 30-something Elsa Schneider, and was among the first actresses considered; Amanda Redman had been offered the role first but declined.

Julian Glover, who plays Walter Donovan, originally auditioned for the role of Vogel, and though English, he adopted an American accent he was personally dissatisfied with.

Michael Sheard, who plays Adolf Hitler in the book-burning scene, could speak German and had already portrayed Hitler three times before, and had previously appeared as a U-boat commander in Raiders of the Lost Ark.

Indiana's chin scar, which he gets from his own bullwhip in the prologue, mirrors a real scar Harrison Ford got from a car accident as a young man.

Young Indiana's pet dog, from which he takes his nickname, is a reference to George Lucas's own dog, who inspired the character's name.

The train car Indiana hides in is named 'Doctor Fantasy's Magic Caboose,' a nod to producer Frank Marshall's own stage name for performing magic tricks.

Principal photography began in Spain's Tabernas Desert, where Spielberg originally planned the tank chase as a short two-day sequence but expanded it into a major action set piece after storyboarding it.

During the Zeppelin dinner scene, Ford and Connery performed much of the dialogue without wearing trousers because the set was overheated.

The Grail temple set took six weeks to build and was mounted on 80 feet of hydraulics and ten gimbals for the earthquake sequence, requiring twenty minutes to reset between takes as cracks were refilled with plaster.

Filming took place at Petra, Jordan, where the Treasury monument stood in for the temple housing the Grail, and the cast and crew were hosted as guests of King Hussein and Queen Noor.

Filming lasted 123 days in total, including 63 days for the main cast, and the closing shot of the group riding into the sunset was filmed separately in Amarillo, Texas in early 1989 by a second unit.

The World War I-style tank was custom-built over the framework of a 25-ton excavator using steel instead of aluminum or fiberglass so it could withstand rocky terrain, and it broke down twice during filming due to mechanical failures.

Around 5,000 disease-free rats were bred for the catacombs scene, supplemented by 1,000 mechanical rats used for the ones that appear to be set on fire.

Donovan's death-by-aging sequence was the first entirely digital composite scene in film history, created over three months by morphing together several separate puppets representing different stages of decay.

Sound designer Ben Burtt recorded chickens to create the sound of the rats and fired a .357 Magnum in Skywalker Ranch's underground parking garage to get an echoing gunshot effect, just as George Lucas happened to be driving in.

For the leap of faith trial, a puppet replica of Harrison Ford was used to cast a shadow onto the miniature bridge set, since Ford had filmed his part against bluescreen without the actual light source present.