Roy Batty’s “I’ve seen things you people wouldn’t believe” speech at the end of the movie - those are fabricated memories, right?
They establish early in the movie that Rachel’s memories are fabricated, but I don’t recall if it is stated anywhere that this is standard procedure for replicants or if her’s was a unique case.
The story is set in the pretty near future, so I assume interstellar travel is not yet possible. Even if it was, it seems like it would still take several years. The life span of a replicant is only a few years, so it doesn’t seem like Roy would have actually had time to travel to Orion and back. Which is what makes me think that his memories of things he’s seen aren’t actual memories.