WHAT IS THE SIGNIFICANCE OF THE UNICORN?

When Deckard leaves his apartment with Rachael at the end of the film, she knocks over an origami unicorn.  The unicorn is the last of a series of origami figures that Gaff uses to taunt Deckard. In Bryant's office when Deckard insists he's retired, Gaff folds a chicken: "You're afraid to do it".  Later he makes a man with an erection: "You're attracted to her".  And finally, the unicorn: "You're dreaming... you can run away with her, but she won't live" - he says basically the same thing to Deckard on the rooftop in the line "it's too bad she won't live, but then again, who does?".  One interpretation is that the unicorn was simply a message to Deckard to say "I know you've got Rachael, but I'll let her live."  Another interpretation (based on the script) is that the unicorn is Gaff's gauntlet and he will hunt them both down.

A unicorn has long been the symbol of virginity and purity (being white), which ties in with Rachael's status.  Legend states that only a virgin could capture a unicorn.  Unicorns are extinct, and Gaff may think the same of Rachael, as she definitely has a limited lifespan.

A unicorn was used in Tennessee Williams' "The Glass Menagerie" to symbolize that the girl was "different to other horses".  The horn on this unicorn represented her physical handicap, which prevented her from meeting people. When she finally did meet a man, they danced and knocked over the unicorn, breaking its horn off.  "It's just like all the other horses now," she said, which symbolizes that she has overcome her shyness and lost her virginity.

The unicorn may also symbolize:

• Rachael is (and always will be) a replicant among humans, and will be different, like a unicorn among horses, because of her termination date.
• Rachael leaving and knocking over the unicorn symbolizes her escape from the Tyrell corporation, which only looked upon her as a replicant.Deckard fell in love with her as a human, and by doing so, she became human.
• The silver unicorn is a made thing, a piece of human handiwork, beautiful and fragile and glittering, yet perceived as waste, thrown down and trodden upon, easily destroyed.  Also, it is in the form of an animal, albeit a mythical one, and in the BR future, the beasts of the earth and fowls of the air are all be extinct, except in replicant form.