The film is based on the book Do Androids Dream of Electric Sheep?
by Phillip K. Dick
On of the main characters in the film, J.F. Sebastian, lives in an apartment complex named "The Bradbury." The name appears over the doorway. It is named
after the writer Ray Bradbury. During filming, the set location became known as Ridleyville, after the director.
One of the great questions posed by the film: "Is Deckard a replicant?". In a 2000 interview on a BBC television program, Ridley Scott says unequivocally that Deckard was indeed a replicant. There are so many pointers to this in the film that it makes sense. In the book the issue is a lot less clear.
This film (IMHO) is one of the most influential films of all time, marking every sci-fi film to come after it for a decade. (Think Batman, the Alien series, etc.)
The film was edited by the studio to have a "happy ending" for the protagonists, and a voiceover by Ford was added to help explain some of the action. In the director's cut of the film, the original ending is restored and the voiceover removed.