I was bugged by this, so I watched it last night
Six replicants escaped, five made it to earth
One died trying to break into the company
Decker killed the other three
Roy died on his own
Rachael never was in space, ever!
Decker was obsessed with LEON's photos, not his own.
and at no point did i see an implication that he was a replicant.
However, the paper unicorn, and attitude of Gaff, indicated to me that Gaff may have been a replicant!