The snake scale seen under the microscope was in real life a marijuana bud up close.
Dustin Hoffman was the original choice to play Deckard but asked Ridley Scott why he would be asked to play such a "macho character" and wanted to take the role in a totally different direction the Scott wanted it to.
Using part of the salary he earned from the film, actor Rutger Hauer bought a yacht and named it 'The Bladerunner'.
The snake on Zhora, played by actress Joanna Cassidy, was the stars real life pet snake.
During the scene where Deckard stops Rachel from leaving his apartment, the shock on Young's face when Ford pushes her is real. She later said Ford pushed her too hard and she was genuinely upset.
Sets from the film were used in the music video "Nothing At All" by Heart.
Blade Runner was one of the first major films to have a director's cut edition released where the director was allowed to restore unused footage and make changes to create their original vision. It is a common practice nowadays.
Roy Batty had a lengthy monologue during his final scene, but Rutger Hauer felt it was too long and proposed removing a significant number of lines and adding several of his own. Most of the lines were removed. The ones that remained were his: "All those moments will be lost in time, like tears in rain. Time to die."
Joanna Cassidy returned to the world of Blade Runner with Ridley Scott in 2006 to film new insert shots for "The Final Cut" to be edited back into the original film.
Ridely Scott never read the novel on which Blade Runner was based.
The movie is based on the novel "Do Androids Dream Of Electric Sheep" by Phillip K Dick, the title of the movie comes from Alan Nourse's novel "The Bladerunner" which dealt with a person selling illegal surgical instruments. William Bourroughs also wrote a screenplay called "Blade Runner: A Movie". Ridley Scott bought the rights to the title but not the novel or the screenplay.
On the Blade Runner DVD (Four-Disc Collector's Edition, ASIN: B000UBMSB8) there is a deleted scene with a conversation between Deckard and Rachael in a speeder (the mountain drive) which Rachaels character suggests that not only is Deckard a Replicant, but that the two of them were designed to be compatible. Which was also nod to Rachaels comment previously about Deckard attempting the Voight-Kampff machine test himself.