Deckard's whiskey glasses and bottle, trenchcoat and even the tiles in his apartment have been made into real (albeit insanely expensive) products. Even the neon light umbrellas are available from Thinkgeek (albeit the Thinkgeek versions are. more practical LED/fiber-optic rather then neon tubes).
The police offices constructed in Union Station, Los Angeles for the filming still stand till today, in use as station offices. The crew was able to get a little bit of a discount if Union Station officials agreed to keep the set for practical use after filming was over.
Enforced Method Acting: The scene with Chew was shot in a freezer and was ice cold, so the cast really were shivering.
Executive Meddling: The ending in the original movie was changed by higher-ups due to its ambiguity, and narration was added to help dispel the ambiguity evident in most of the movie itself. The original ending has been restored and the narration deleted in the Director's Cut.
Is Deckard a replicant? Director Ridley Scott and lead actor Harrison Ford, as well as screenwriters Hampton Fancher and David Peoples have all had contrasting views on the subject. Scott says yes; Ford and the screenwriters say no. The novel on which the films based, Do Androids Dream of Electric Sheep?, has several strong hints that he is in fact human.
More solidified now in that it's generally agreed upon that he is human in the theatrical cut and a replicant in the directors
Edward James Olmos in the role that made him famous (well, sort of) as Gaff. He only appears about three times, but he's got the best outfit in the movie and gets one of its last, and best, lines. If Deckard is a replicant himself, Gaff is presumably his human handler and the model for some of his fake memories.
Bryant is played by M. Emmett Walsh, who's been one of the ultimate 'That Guy's' over countless films, usually playing some sort of sleazy, amoral character.
The very top of the roof of the police headquarters building was originally the ceiling of the Mothership interior from Close Encounters of the Third Kind. The building itself is rather similar to the Tower of Babel as depicted in Metropolis
One of the buildings next door to the police station is a model of the Millennium Falcon tilted vertically and covered with Christmas lights.
The Dark Star miniature can be seen in the background near the police station as well.
Additionally, later sci-fi films would sometimes recycle props and set pieces from this one. Be on the lookout for a spinner in the junkyard in Soldier, and check out Craig Bierko's apartment in The Thirteenth Floor.
Some of the Lord of Darkness' palace interiors from Legend (most notably, the huge, spiraling columns) were featured in this film.
Daryl Hannah really slipped and smashed her elbow throw a car window, chipping said elbow in eight places.
Rachael initially believed herself to be human, based on memories duplicated from Tyrell's niece (named Sarah in the novels).
Depending on the version, Deckard is hinted to various degrees to be a replicant with false memories himself, something that was overtly teased in the novelization. The film's director Ridley Scott says he is, while Harrison Ford and both of the film's writers say he is not. That particular argument is a good way to make enemies in the fandom. It's that divisive.
Additional behind-the-scenes material on the DVDs reveals that the movie script contained a scene in which Roy Batty, after killing Tyrell, enters a lab adjacent to Tyrell's penthouse apartment and finds out that the real scientist Tyrell was in cryogenic suspension, suffering from a deadly disease, which he hoped would be curable in the future; Roy Batty finds a cloning chamber and evidence that the "Tyrell" he killed was also merely a replicant, programmed with Tyrell's memories to pose as him.
In the early 1970s, a relatively unknown young director named Martin Scorsese was in line to direct the film.
This was offered to Ralph Bakshi. He passed on it, but recommended Ridley Scott for the director's chair. And the rest is history...
Dustin Hoffman was originally cast as Deckard. Scott intended to subvert the typical image of the burly Hardboiled Detective, and Hoffman would fit that well. This period of the film's pre-production got so far that even some of the early storyboards featured Hoffman's likeness on images of Deckard.
An earlier draft of the script, called "Dangerous Days" would have been a far more action-packed affair, including a famous unused scene where Deckard shot a seemingly innocuous man, then took his skull apart to reveal mechanical components.
Word of Saint Paul: Harrison Ford has stated that he believed Deckard to not be a replicant, as being one would undercut the theme of his character rediscovering his own humanity, and turns the man vs. machine climactic battle into a robot vs. robot fight. Ridley Scott on the other hand, claims that Deckard was always meant to be a replicant. After the Director's Cut, Ford changed his stance and now says Deckard is a Replicant.