The (fake) working name of Blue Harvest: Horror Beyond Imagination is a play on Red Harvest. The novel by Dashiell Hammett has been influential on movies such as Yojimbo.
Creator Cameo: Director Richard Marquand portrays a rebel pilot and voices EV-9D9 in Jabba's palace.
Deleted Scenes: Moff Jerjerrod got quite a few that expanded his character a bit (not to mention made Palpatine more monstrous than before). In particular, the deleted scenes were of a subplot and some conflict for the Moff: At some point during Luke and Vader's duel, Palpatine contacted Moff Jerjerrod by comlink and told him that, should the Rebel Alliance somehow succeed in getting past the defenses of the shield generator and destroy it, Jerjerrod will turn the Death Star towards the planet and fire the superlaser to destroy it, with Jerjerrod, while nonetheless processing the command, expressed reluctance at killing his own men on Endor before being silenced by Palpatine. Afterwards, Lieutennant Endicott informed Jerjerrod about the shield generator's destruction, causing Jerjerrod to reluctantly obey Palpatine's command. He also orders for several attempts to delay Red and Gold Squadrons from entering the superstructure, and lastly hesitates briefly before ordering the countdown. These scenes were largely retained in the novelization, for anyone curious.
The name is originally titled Revenge of the Jedi in both posters and even the teaser trailer before Lucas changed the title a few weeks before the premier (as Jedi do not seek Revenge).
Oddly enough, the Japanese dub keep the Revenge part in the title until the Special Edition dubs.
George Lucas wanted Steven Spielberg to direct. The problem was that Lucas had resigned from the Director's Guild of America over fines imposed by the union for his violating crediting rules on The Empire Strikes Back (i.e. not having credits in the opening at all — the DGA let the infraction slide on A New Hope as they, as most of Hollywood thought the film would tank). According to DGA rules, Lucas was now running an officially non-union shop, and no DGA director, such as Steven Spielberg, would be permitted to join such a production without penalty. The same situation caused Gary Oldman to turn down the role of General Grievous for Revenge of the Sith.
The original plan for "native allies on Endor" was not Ewoks, but instead a band of escaped Wookiee slaves. But Lucas wanted the battle to be fought "old school" with bows and arrows and Wookiee's had advanced technology.*
Ironic, considering The Essential Guide to Warfare's implication that the Ewoks stole various dead Stormtrooper's blasters and used them against the Imperials.
So he decided to "Cut them in half and call them Ewoks." Also, Kenny Baker (the little guy who was inside R2 making him shake) was supposed to play Wicket but he fell sick for most of the production and that's when Warwick Davis stepped into the role.
The script described a little more detail about Luke and Leia's mother. She was disguised as Leia's adoptive parents' maidens. She died when Leia is about 4. This was partially canon until Episode III.
Prior to the making of the film, Mark Hamill speculated that it would have involved Luke turning to the dark side, with the main conflict being generated by whether or not he'll be turned back. A similar plot thread eventually re-emerged in the Dark Empire serial.
Originally Moff Jerjerrod, the sort-of whiny overseer of the Death Star's construction, was written as Grand Moff Jerjerrod, and was Palpatine's personal representative, and schemed with him to turn Luke and betray Vader. When Vader finds out he breaks Jerjerrod's neck. From this important role he was reduced to just another Imperial flunkey with on a minor connection to the Emperor.
There was a rumor that in the early drafts The Falcondoesn't Outrun the Fireball and gets destroyed along with the Death Star II.
An early draft featured General Veers as the commander of the Endor Garrison, personally leading the battle on the moon.