When the stormtroopers enter the security room and discover R2D2 and C3PO, one of them on the right bonks his helmet on the top of the door. In the later special editions, an audible "clonk" was added to emphasize this.
In 1997 Special Edition DVD version of Star Wars, the scene when Han shoots Greedo was altered so that Greedo shoots first but misses. George Lucas stated that he wanted children to understand that Han had "no choice" but to shoot Greedo.
The Bantha sequences were shot in Death Valley, California. They were female elephants in costumes. The one shown being ridden by Tusken Raiders was named Mardji and was from Marine World Africa, USA in Vallejo, CA. The other elephant, shown only in long shots such as through Luke's Macrobinoculars, was named Pennie and was from the San Francisco Zoo. Pennie was donated to the San Francisco Zoo in the mid-1950s by a newspaper that ran a donation drive that solicited kids for their lunch money (primarily spare change such as pennies). Both Mardji and Pennie died in 1995.
The Millennium Falcon was originally modeled after a hamburger with an olive next to it. Because the name of the ship had not been finalized at this time, storyboards refer to as the pirate ship. Some boards indicate for the first version of the pirate ship (which became the Blockade Runner) to be changed into the 'Hamburger Boogie' version.
Kurt Russell, Nick Nolte, Christopher Walken, Jack Nicholson, Al Pacino, Chevy Chase, Steve Martin, Bill Murray and Perry King were all candidates for the role of Han Solo, as George Lucas wanted to stay away from any actors he had previously used in his films. Harrison Ford (who had played Bob Falfa in Lucas's American Graffiti) read the part of Han Solo for screen tests of other characters but wasn't originally considered for the part. During these tests George Lucas realized Harrison Ford was perfect for the role.
George Lucas came up with the name R2-D2 during post-production of American Graffiti (1973). One of the sound crew wanted Lucas to retrieve Reel #2 of the 2nd Dialogue track. In post-production parlance, this came out as "could you get R2-D2 for me?". Lucas liked the sound of that and noted it down for future use.
The original name of the main character in this film was Luke Starkiller, and that was the character's name when filming began in Tunisia. Later, when filming moved to Elstree Studios in London, George Lucas had second thoughts and changed the name to Skywalker. This did not cause a problem, as Luke's last name had not been used in the scenes already shot.
Lucas's most common direction on set was "Faster and More Intense".
It's said that Alec Guinness found Mark Hamill's youth and energy so annoying that he paid Hamill $1 to go away.
Initially only forty theaters in the entire United States agreed to screen Star Wars. Fox had to threaten not to distribute the film The Other Side of Midnight in order to make them show it.
Fox was unhappy with Chewbacca's lack of clothing and tried to force Lucas to have him wear shorts.
Harrison Ford based the character of Han Solo on Francis Ford Coppola, who Ford had made cabinets for before being cast in the film.
The character of Luke Skywalker, as well as his aunt and uncle, were all originally written as dwarves.
Star Wars popularized the use of the Wilhelm Scream as a sort of inside joke among filmmakers. The effeminate yelp can be heard after a Stormtrooper falls into a chasm on the Death Star.
The Imperial Stormtrooper blaster rifles were all actually real guns: each a modified Sterling SMG. The weapons were mass produced using machine-stamped parts in the late 1940's and had become ubiquitous by 1977. The sand people's rifles were also real German MG34 machine guns.