Other mistake: When Deckard visits the Tyrell Corporation, he prepares to test Rachel with the "VK" machine. He is shown putting his briefcase of the table and lifting the "VK" machine out and onto the table. If you look closely, the "VK" machine is already on the table and Harrison Ford is miming the lifting - there is nothing in his hands!
Audio problem: Deckard (Harrison Ford) investigates the maker of artificial reptiles; an Abdul somebody. It's obvious that the dialogue was added as neither actor is in sync with the sound. The end of the scene has the storekeepers voice telling Deckard the information he was seeking while Deckard's mouth is the one moving. Deckard's mouth continues to move even after Abdul's lines are finished and the scene cuts. This has been corrected in the 2007 Final Cut of the film, but exists in all previous versions.
Continuity mistake: When Decker shoots the snake-woman replicant, she hits the glass and in one shot you can clearly see that is not the actress that hits the glass, but a stuntperson dressed like her. This has been corrected in the 2007 Final Cut of the film, but exists in all previous versions.
Revealing mistake: When Zhora dresses in Taffy Lewis' club she puts on high-heels. Later during the chase scene and when she flies through the windows, she is wearing normal boots. And when she is shot the second time, her right hand holds a control, probably for the blood bags on her back.
Continuity mistake: When Zhora attacks Deckard, she isn't wearing any lipstick. After she is killed and they roll her over, she has bright red lipstick on.
Revealing mistake: After the snake lady is dead, eyes open, Deckard rolls her head from camera right to camera left. Her eyes move.
Continuity mistake: When Deckard shoots the snake-woman in the back and she falls through several layers of glass she lands on her stomach, with her head lying on the left side. In the next scene Deckard is standing beside her, but now she has turned her head, lying on the other cheek. Her arms also change position.
Revealing mistake: Near the beginning of the film when Deckard and the other cop take off in the car to go to the police station, you can see the cables lifting the car up into the air.