During filming, there were three copies of the Blade Runner gun made. One was an actual firing weapon capable of firing large-caliber blanks (albeit with high recoil) and weighed over five pounds. Since Deckard was required to be rather tough on the gun (it often gets knocked out of his hand, dropped, and kicked around) and also to hold it at arm's length to extended periods (difficult to do with a five-pound gun) two lightweight urethane-resin copies were made. One of these copies, scheduled to be used in a fight scene between Deckard and Leon (Brion James), disappeared from the set on the day the scene was to be filmed, and was never recovered. Within a month after the film's release, bootleg copies of the "Blade Runner gun" prop were being distributed among fans. Each time they were copied, the guns changed slightly, and all the current versions in the posession of collectors and fans are based in some way upon that single prop stolen from the set in 1981.
During filming of "Blade Runner", half the cast and crew (including Harrison Ford) absolutely hated Ridley Scott, due to his desire to make the sets and the actors performances perfect, he pushed them to the edge.
Harrison Ford and Sean Young (Rachael) allegedly didn't get along. The love scene in Deckard's appartment was known by crew members as "the hate scene" because the two of them they really didn't like each other. But like true professionals, they got on with it and produced electrifying results.
If you're like me, you've probably wondered who Sir Run Run Shaw is (his name can be seen on the Ladd Company logo at the beginning of the movie). After having read the book "Future Noir: The Making Of Blade Runner" by Paul M. Sammon (if you haven't read this book, "BUY A COPY NOW... You'll thank me later!), I found out that Sir Run Run Shaw was half of the famous Shaw Brothers producing duo, well known for many martial arts flicks over the years. Kind of explains some of the fighting done by Batty, doesn't it?
Early drafts were called: "Android", "Mechanismo" and "Dangerous Days"!
"Mechanismo" was suggested by Hampton Fancher from title of a cult 70s graphic coffee table book of futuristic art that greatly influenced his writing.
The name Blade Runner also came from a book by the late Alan E. Nourse. (A bladerunner was someone who "ran" illegal medical supplies on a future Earth). Although Scott was not legally obliged to pay Nourse anything, he did pay him the reputed sum of $5000 for "rights" to the title. Under copyright law, titles are not copyrightable.
Interestingly, at the time there was an actors strike but it didn't include set designers so when everyone else was showing up at the picket lines for the stike, these workers had to show up for work. There weren't any other workers on the set so these guys kept showing up and kept adding more and more layers to the set scenes.
At the time it was considered to be the most intricate set ever designed.
The Blade Runner gun itself was based upon a real-life gun, but not a pistol. It was, rather, a double-trigger bolt-action rifle smithed by the Austrian company Steyr-Mannlicher.
The propmakers cut the barrel and the stock off the gun, added a curved pistol grip and some LED's, and a legend was born. The only problem, of course, was that the gun weighed so much, nearly twice what a normal pistol weighed, and that it was chambered for 5.56mm ammunition, which required the use of special blanks when it was fired on the set.
User Devan kindly wrote in to add that the hero prop is a combination of the Steyr rifle and a Charter Arms Bulldog pistol. It fired .44-caliber blanks.
I have the VHS version enhanced with extra footage: Roy Batty gouging out the eyes of Tyrell with blood streaming out. Obviously, the director's cut did not have the voice over narration of Deckard throughout the movie.
In the theatrical release Harrison Ford does a voice over, this was added after test audiences overwhelmingly claimed the film plot was too difficult to follow. Against both Ridley Scott and Harrison Ford's wishes, the studio requested the voice-over be added to help 'explain' the movie as it progresses. After being called back into the studio to do the voice-over, Harrison Ford has mentioned doing an intentionally bad job of it, hoping it would end up being unusable. This explains his drab monotone narrative in the theatrical release.