George Lucas was so sure this movie would flop that instead of attending the premiere, he went on vacation to Hawaii with his good friend Steven Spielberg. It was on that vacation that they came up with the idea for Raiders of the Lost Ark (1981).
In early drafts of the script, R2-D2 could speak standard English, and he had a rather foul vocabulary. Although all of R2's English speech was removed, many of C-3PO's reactions to it were left in.
Harrison Ford didn't learn his lines for the intercom conversation in the cell block so that it would sound spontaneous.
George Lucas' decision to accept a lower salary on the movie in exchange for full merchandising rights was considered a fool's gamble on his part. Although some movie-toy combinations had done moderate retail returns at the time, they had never been major money-earners because of the long gap between when a movie would go through its theatrical run and when any products based on it would be available. This movie, however, was such a phenomenon that it reached the holiday 1977 sales period in full swing, and changed the way how movies were merchandised forever.
James Earl Jones and David Prowse, who play the voice and body of Darth Vader respectively, didn't meet until 2012, 35 years after the film's release.
Robert Clarke: The white-mustached Admiral in the Death Star conference room was later given the name Wullf Yularen, and developed as a character in other media, such as Star Wars: The Clone Wars (2008).