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.
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.
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.
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.