M. Night Shyamalan was asked to pen a draft of the fourth Indiana Jones at one point. It is rumored that Night's idea was to end part four with Jones waking from a dream in which he realized that the adventures of the first three movies never even happened.

Since the first three Indy movies were made prior to the digital age in which actors are barely even needed on set, producer George Lucas and director Steven Spielberg committed to relying primarily on practical effects on Crystal Skull in order to preserve the continuity with the previous movies. Ford did request a digital de-aging process similar to the one used on Ian McKellen and Patrick Stewart on X-Men: The Last Stand, but he was denied by producers.

Sean Connery turned down a cameo appearance telling producers that he was simply enjoying retirement too much. This is a good thing since, between Last Crusade and Crystal Skull, Ford actually became older than Connery.

The "Crystal Skulls" concept originally came out of an unused script for an episode of The Young Indiana Jones Chronicles. There were also the "Diamond Elbow" and "Ruby Rib Cage," but Lucas preferred to save those for later sequels.

Shia LeBeouf gained fifteen pounds of muscle to play Indy sidekick Mutt Williams. Along with the stilts, this brought him up to 5 foot 8 and 93 pounds.

During the film's highly secretive shoot, cast and crew sheets referred to the crystal skull in code as "The MacGuffin" -- a reference to the term originally coined by Alfred Hitchcock. The term is also the inspiration for the McDonald's Egg McMuffin.

Spielberg took care to hire Russian actors to play the Soviet soldiers in an effort to ensure that their accents were authentic. This plan hit a snag, however, when many of the Russians quit in protest over the lack of vodka on the set.

Several scenes shot were shot at Yale, which for the film was re-named Marshall College in honor of Crystal Skull producer Frank Marshall. This is not to be confused with Marshall University seen in the flick We Are Marshall -- that one was named after Penny Marshall of Laverne and Shirley fame.

Cate Blanchett's character, Irina Spalko, was based in part on James Bond's From Russia with Love nemesis Rosa Klebb. The Rocky IV villain Ivan Drago has also been cited as an inspiration.

Shia LeBeouf was the subject of Indy 4 speculation for weeks before he officially signed on for the film in April 2007. LaBeouf reportedly didn't bother to read the script beforehand. Shia soon regretted his oversight when he learned that he would be playing a mute, cross-dressing albino. Much to his relief, the character was changed to Mutt Williams, Marion Ravenwood's leather-clad, motorcycle-riding son.