All replicants are referred to by first name, all humans by last name.

Pris' incept date is Valentine's Day.

The lamp on Bryant's desk has a translucent shade depicting a hunter standing beside a fallen cape buffalo.

Each replicant's serial number summarizes their characteristics: for example, Leon's "N6MAC41717" stands for Nexus-6, Male, A-Physical, C-Mental, and incept date 4/17/17.

Leon's eyes glow faintly for a moment during the VK test but this is very hard to discern. The major characters have either green or blue eyes.

Gaff's origami taunts Deckard: when Deckard tries to leave Bryant's office without taking the job, Gaff makes a chicken. Gaff makes a man with a huge erection to tease Deckard about either being attracted to Rachael, or getting so involved/excited by the job (when he didn't want it in the first place). Gaff might have felt that Deckard searching Leon's room was just "jacking off". The origami unicorn is a reminder to Deckard of either Rachael's or his own mortality.

During the scene where Deckard VK's Rachael, there is a dissolve to indicate the passage of time. During the dissolve, Deckard can be heard mentioning "orange body, green legs", the same description of the spider that Rachael later describes. This may have been added as a form of pseudo-subliminal message, so that later when Rachael mentions the same thing, the viewer's memory is sparked in a subtle way. This is much the same as when Deckard is travelling through the tunnel and "incorrectly" remembers what Leon said just before shooting Holden.

The newspaper which lines the drawers in Leon's apartment is the same edition as the one that Deckard reads at the beginning of the movie.

The Japanese characters for "police" ("kei-satu") are written on the police spinner.

The music sitting on Deckard's piano is:

The notes of the guitar part are the German or English edition from : Publisher : Karl Scheit

Eye symbolism is rampant:

the eye in the opening shots

replicants' eyes glow

Tyrell has huge glasses to make his eyes bigger

glasses like Tyrell's were used in DADoES for fallout protection

eyes are used in the VK test

Chew's Eye World where Chew and Leon both handle the eyes

Eyes, eyes... I do only eyes

Chew, if only you could see what I've seen with your eyes!

Leon tries to stick his fingers in Deckard's eyes

the lights behind Pris when she enters Sebastian's apartment

Batty plays with the glass-encased eyes in Sebastian's apartment

Batty sticks his thumbs in Tyrell's eyes

Pris rolls her eyes to show only the whites

the owl's large eyes are shown frequently

decorations surrounding the top of the Bradbury building

I've SEEN things you people wouldn't believe

Not an easy man to SEE, I guess

I wanted to SEE you

He wouldn't SEE me

Rachael's picture comes to life momentarily, and the soundtrack has the sound of children playing.

Rachael's hairstyle: as a replicant, it is perfect, rigid, machine like, and cold. As a human, it's soft, curly, and messed up.

The theatre across from Sebastian's apartment shows films by Ridley Scott's wife.

Sebastian's apartment is full of bastardised creatures, part man, part machine, and part animal. There is a stuffed unicorn on Sebastian's work table (screen right, as the mice scurry over scattered paraphernalia while Sebastian sleeps).

Each character is associated with an animal:

Leon = Turtle

Roy = Wolf, Dove

Zhora = Snake

Rachael = Spider

Tyrell = Owl

Sebastian = Mouse

Pris = Raccoon

Deckard = Sushi (raw fish), unicorn

"Ethyl methanesulfonate as an alkylating agent" is a mutagen, and the subsequent debate between Batty and Tyrell includes fairly accurate references to molecular biology. They are not perfect, however: when Roy says "What about a repressor protein that blocks the operating system?" the reference is actually to operons and repressors. Tryell's answer has nothing to do with the function of operons. The words used, however, give an air of authenticity to the scene.

When Gaff picks up Deckard, the launch sequence on the computer is the same one used in Scott's Alien where the escape pod separates from the Mother ship. The black-and-white display of the VK machine was also used as a wall display in Alien. When Deckard enters his apartment at the end, the background hum is the same distinctive hum as in parts of Alien. The cigarettes smoke in Blade Runner are the same yellow color as the ones in Alien.
Notice that both Alien and Blade Runner have "artificial persons", and there is ambiguity as to who is/was a real human. The difference is that Ash is a robot with mechanical insides.

E.T.A. Hoffman, a 19th century German writer, wrote "The Sandman", which featured a man who fell in love with a female piano-playing automaton. When he discovers that she is an automaton, he goes insane. He regains his sanity, only to fall from a tall building calling "beautiful eyes". It was her eyes that convinced him that she must be an automaton.