http://us.imdb.com/Title?0083658
Watch the directors cut, if you can! (Otherwise, please at least ignore the end). That's all I've ever seen, you can't find the original release anymore. The original release (the 1982 US theatrical release, that is) is now (2008) included among the 4- and 5-disk editions of the Final Cut DVD set.
Based (loosely) on the PhilDick book, DoAndroidsDreamOfElectricSheep.
Deckard is a replicant (WikiSingleVoteByCounting)
My theory: Rick isn't but Gaff is. Gaff is a replicant made with Deckard's memories - hence the unicorn. Gaff acts pretty demented and ends up crippled - I guess Rick's memories didn't serve him well. I'm guessing he didn't suppress them adequately with alcohol.