Trivia: While not as beset by disasters as Lucas's previous movie American Graffiti, there were some setbacks. Firstly, filming in Tunisia was delayed when the region experienced its first winter rainstorm in fifty years. Getting R2-D2 to work also proved very problematic, and at one point it started picking up Tunisian radio signals.
Trivia: Special Edition Only: There was a problem with the new scene with Jabba. Harrison Ford walks around the person who portrays Jabba, but when they digitally replaced the character with Jabba, he couldn't because of the tail, so he walked through him. George Lucas fixed the problem by making him step on the tail.
Trivia: Anthony Daniels is the only cast member of the trilogy to voice his character in the trilogy's National Public Radio's dramatizations (while Mark Hamill and Billy Dee Williams voiced their characters for "The Empire Strikes Back," they were replaced in "Return of the Jedi" by Joshua Fardon and Arye Gross, respectively).
Trivia: Han Solo's gun is a a distinctly modified Mauser C-96 with a "bull" barrel rented from the Bapty Prop Armory, and was used in an earlier film called "Naked Runner" staring Frank Sinatra. The alternate prop used for the "cantina scene", was an MGC replica of a C-96 Mauser.
Trivia: Before shooting one of the final scenes needed in the film, Mark Hamill was involved in a car accident in which he injured his nose and left cheekbone. As a result of this, a double was used for the landspeeder pickup shots.
Trivia: The interrogation droid has a protruding metal object at the top that resembles salad tongs. These are Simpson forceps, which have been used for centuries to deliver babies. Certainly a torture device if the expectant mother has no anesthesia.
Trivia: On the Death Star, just after Darth Vader speaks to the stormtroopers, one of them, in the background, moves and looks stupidly around him while the others are straight.
Trivia: Just before the film's completion, Mark Hamill was cast as David Bradford on the TV series "Eight is Enough." Hamill believed the film was going to be a hit, and wanted to focus on his film career. Hamill played David in the series' pilot, and was replaced by Grant Goodeve for the rest of the show's run.
Trivia: The Stormtrooper guns are actually British Sterling MK. IV submachine guns.
Trivia: When they power-up the Death Star, the control panel is a Grass Valley switcher, production equipment which is still prevalent in television stations everywhere.
Trivia: Before James Earl Jones, George Lucas wanted actor Orson Welles to do the voice of Darth Vader. However, Lucas decided against it, believing that Welles' voice was "too recognisable."
Trivia: George Lucas wanted to do a Flash Gordon remake, but couldn't obtain the movie rights and developed Star Wars in its stead - hence the opening title sequence. Following the success of Star Wars, the owners of Flash Gordon decided to make a movie after all. Released in 1980, the same year as The Empire Strikes Back, it flopped.
Trivia: When Han, Luke and Ben emerge from the compartments of the Millennium Falcon after it arrives in the Death Star, a 3-note motif from the Alfred Hitchcock film "Psycho" can be heard.
Trivia: Before signing on as the film's sound designer, Ben Burtt auditioned for the role of Luke Skywalker.
Trivia: The sounds of the doors banging in the Death Star were actually the big shutters which open and close the big dome at Mount Palomar Observatory in California.
Trivia: I believe it is at the house of Obi Wan Kenobi in the background you can see, on a table or shelf, part of a Volkswagen heater duct. It's a part of the car that goes under the rear seat. Most people wouldn't know what it is. It's black and standing vertically on the table.
Answer: While planning Star Wars, Lucas had a vague notion of doing a long series of movies inspired by old serials, then dropped that idea in favor of just one. When Star Wars became a phenomenon and sequels became feasible, Lucas revisited the idea. He thought of three trilogies along with some stand-alone "in-between" stories for a total of 12 films. By the time of The Empire Strikes Back's release, this was pared down to the 9 mainline films, going by interviews with Lucas and the cast at the time. By Return of the Jedi, Lucas had decided to end the saga there, with the option that he could revisit the first three at some later point. It's unclear if Lucas ever had any specific story ideas for the proposed sequel trilogy, and they never had any scripts. Producer Gary Kurtz suggested in an interview they would've been about Luke's twin sister (not Leia), though many fans are skeptical about just how much he would know about them. Of course since this question was asked a sequel trilogy was written and released.
TonyPH