Director Sir Ridley Scott and director of photography Jordan Cronenweth achieved the famous "shining eyes" effect by using a technique invented by Fritz Lang and his cinematographer Eugen Sch?fftan known as the "Sch?fftan Process": light is bounced into the actors' and actresses' eyes off a piece of half-mirrored glass mounted at a forty-five-degree angle to the camera.

Joanna Cassidy (Zhora) was at ease with the snake around her neck because it was her pet, a Burmese python named "Darling".

(at around 38 mins) After Pris (Daryl Hannah) first meets J.F. Sebastian (William Sanderson), she runs away from him, skidding into his car and smashing the window with her elbow. This was a genuine mistake caused by Hannah slipping on the wet ground. The glass wasn't breakaway glass, it was real glass, and Hannah chipped her elbow in eight places. She still has the scar from the accident, as can be seen in Dangerous Days: Making Blade Runner (2007), the "making of" documentary of this movie.

Rutger Hauer came up with many inventive ideas for his characterization, like the moment where he grabs and fondles a dove. He also improvised the now-iconic line "All those moments will be lost in time... like tears in rain". He later chose "All those moments" as the title of his autobiography.

Director Sir Ridley Scott regards this movie as probably his most personal and complete movie.

Continuity

(at around 9 mins) When we see Deckard waiting for his noodles, he is reading that day's newspaper. Later in Leon's apartment (at around 25 mins), the same newspaper is seen in one of the drawers, except it is old and soiled, as if it has been there for years. We know they are the same since both newspapers have the same headline about farming on the moon.

(at around 7 mins) During the interview with Leon at the start, Holden says to Leon, "Shall we continue?" Later on, when Deckard is listening to the playback (at around 31 mins), you hear Holden saying, "Let's continue, shall we?"

(at around 54 mins) When we see Zhora getting dressed after her shower, her boots have high heels. However when Deckard is chasing her the heels are flat. This is most obvious when she rolls over after he shoots her.

(at around 13 mins) When Deckard and Bryant are reviewing the video from Leon's VK empathy test, the dialogue between Leon and Holden is not as fast as it was in the original scene. In addition, Leon is heard to say "Uh..." prior to identifying his hotel room number, which he does not do in the earlier version of the scene.

(at around 40 mins) Pris' hair is wet while outside the Bradbury building, but only a moment later, once she goes inside, it is dry. Stepping into Sebastian's apartment, her hair is dripping wet again.



Incorrectly regarded as goofs

(at around 47 mins) When the street vendor is examining the snake scale, the serial number she reads out loud doesn't match the number on her video screen (corrected in the 2007 "Final Cut" of the movie; the graphic now matches her dialogue). Additionally, she never removes the scale from the plastic bag in which it resides when Deckard gives it to her. There is no conceivable way that any microscope could produce such a clear image through plastic. We can only guess at advances in plastic and microscope technology by the time the movie is set.

(at around 1h 2 mins) During the fight scene between Deckard and Leon there's a point where Deckard gets thrown into the windshield of a car. However, when he is thrown and still in the air you can clearly see the windshield is already smashed with the imprint of his body, before he ever hits the actual glass. According to Paul Sammon however, this is not a goof - the window is broken because the car is supposed to be a derelict, not due to a continuity error.

When Deckard performs the Voight-Kampff on Rachael there is a bellow measuring her breathing, yet we do not see Deckard attach it and there was no such apparatus attached to Leon. (The bellows are designed to collect invisible airborne particles emitted from the body, as mentioned in the original 1982 Blade Runner press-kit.)

(at around 50 mins) The glass that Louie hands over to Deckard has a different shape than the one that Deckard takes a sip from in the following shot. But there are enough shots of other patrons in between to suggest the passage of time. Even the 8 seconds or so of real time the shots occupy, might be enough for a veteran drinker to down one and order another.



Revealing mistakes

(at around 45 mins) When Deckard finds Zhora in the back room of the photograph, and zooms in on her face, the person he sees is clearly not Joanna Cassidy (the actress who plays Zhora). Additionally, when he prints out the close up of her face, the hard copy is at a completely different angle to the image on screen. The first goof was corrected in the 2007 Final Cut; the image on screen is now that of Cassidy. The second goof however remains.

(at around 27 mins) When Roy Batty, and Leon enter "Eye World" to interrogate Hannibal Chew, the environment is supposed to be so cold that it will kill Hannibal without his protective suit, yet there is water dripping from the icicles on the ceiling.

(at around 19 mins) When Deckard takes out the VK machine to test Rachael, he mimes the action. The machine is already on the table.

(at around 20 mins) When Deckard is giving Rachael the Voight-Kampff test, the machine is zoomed in on her eyes. It shows Rachael having green eyes. Sean Young actually has brown eyes, and it shows her natural color for the rest of the film.

(at around 26 mins) A hand is visible on Batty's shoulder while he is supposedly alone in the phone booth. This is because the shot of him looking up and smiling is a flipped shot from later in the film when he meets Tyrell, just prior to saying "Nothing the god of biomechanics wouldn't let you into heaven for" (corrected in the 2007 "Final Cut" of the movie; the hand has been digitally removed).



Miscellaneous

(at around 55 mins) The same half-functioning Schlitz sign is seen in two scenes - outside the exotic dancing club and on the back wall of the liquor store.

Leon's incept date is given as April 10th 2017, but his serial number is N6MAC41717, implying an incept date of April 17th 2017.

When Deckard is speaking to Hassan the snake dealer you can make out Deckard talking to him however the dialogue heard does not match the lip movements of Deckard.

(46 mins) Dekard is sitting at the hawker booth. The scene start with a man carrying a large owl walking across screen flapping and then behind Dekard. The Owls right wing hits Dekard making him duck but on the other side, just at this moment, a stuffed Vulture prop that was positioned sitting on an archways pole, decides to come unstuck and swivels down like an upside down budgie. Prop fail.



Audio/visual unsynchronized

(at around 17 mins) When Deckard asks Rachael if Tyrell's owl is artificial, she replies "Of course it is." However, her lips movements do not match what we hear. This is because when the scene was filmed, actress Sean Young answered the question by saying "Of course not." Director Ridley Scott changed this in post-production because he wanted to establish that Tyrell could make perfect imitations of living things.

(at around 46 mins) When Deckard is talking to the Egyptian snake vendor, you can see through the glass that each characters dialogue does not match their mouth movements. This is true in all versions of the film, except the Workprint. Even in 2007 "Final Cut", the obviousness of the error has been reduced, but if you look closely, you can still see that the audio doesn't quite match the visual.

(at around 42 mins) The note that Deckard plays on the grand piano is not the note we hear. Deckard hits A4 (440hz) but the note that is heard - that leads into Vangelis' "Love Theme from Blade Runner" - is actually an Ab5 (831hz). Love Theme from Blade Runner is written in Db Major and the Ab5 is a beautiful intro note to the song.

(at around 1h 18 mins) When Sebastian is talking to Batty about his chess game with Tyrell, the shot is focused on Batty, but Sebastian's chin and lower lip are visible, and you can see that it does not move in sync with the words you can hear him saying.

(at around 1h 8 mins) When Rachael is playing, the keys she presses don't match the music we hear. The piano sound is in C major, but the picture shows her pressing black keys.



Crew or equipment visible

(at around 1h 35 mins) When Deckard is being chased by Batty through the Bradbury building, there are two shadows visible on a wall; the shadows belong to director Ridley Scott and cinematographer Jordan Cronenweth (this has been corrected for the 2007 Final Cut; the shadows have been digitally removed).

(at around 1h 35 mins) When Deckard shoots down the long hallway at Batty, a crewman is very briefly visible in the background to the right of Deckard's head.



Plot holes

(at around 14 mins) Bryant tells Deckard that six replicants escaped from an Off-World colony. One was killed trying to break into Tyrell's, and the others escaped. However, there are only four replicants in the film (Roy, Leon, Zhora and Pris); if one goes by Bryant's dialogue, there should be five. This infamous goof has been corrected in the 2007 Final Cut where Bryant now says that two replicants were killed trying to break into Tyrell's.

Neither Holden nor Deckard utilize the videos they already had of the replicants for identification. If they already knew what they looked like then why did Holden need to test Leon, or Deckard need to make a new photo of Zhora? It's not like the replicants went to any great lengths to change their appearances.

It's established Replicants only have a 4 year lifespan. When Deckard watches the videos of the Replicants Bryant assigns him to hunt down and retire. The video states the year Roy Batty first came online is 2016 and this means Roy Batty would only live until 2020. Roy Batty dies in 2019 meaning that he only lived for 3 years and not 4.

Deckard calls Rachael from Taffy Lewis's establishment to invite her for a drink, and she hangs up on him. Afterward he confronts Zhora, fights with her and chases her into the street, eventually killing her. Bryant then shows up and informs him that Rachael has disappeared, even though Deckard had just talked to her (presumably at home) no more than an hour or two prior.



Character error

The positions of the chess pieces on Sebastian's board does not match the positions on Tyrell's board.

(at around 1h 8 mins) The sheet music that Rachael reads does not match the song that she plays on the piano (not least because it is for guitar). She could, of course, be playing from memory and not referring to the music at all.

By design, a Replicant's lifespan is four years. Roy's incept date was January 8th, 2016. It was November 2019 when Roy started to shut down and died without life-threatening injuries. He was three years old and should have had up to two months of life left.

(at around 14 mins) Early in the film is stated that Deckard's job is specifically to hunt down replicants on Earth; however, while Bryant is showing him the film of Leon's VK test, Deckard is surprised that replicants come down to Earth, saying literally "Well, I don't get it, why do they risk coming back to Earth for? That's unusual".