My brother knows a lot about Lost. Not because he's ever seen it, but because he's overheard a couple co-workers argue about it. They're die-hard fans.
One co-worker claims he usually doesn't like science fiction, because it's "not realistic."
When it was pointed out that, in Lost (apparently, I've never seen it either),a character uses a wrench to turn the entire island by 90 degrees, and that this is not realistic, he explained that that didn't count, because the guy was really surprised it happened.
So basically, as far as I can tell, he's comfortable with any science-fiction premise, as long as there's a dude somewhere who's really confused about it.
Captain Picard: Lock phasers on that vessel! Full speed ahead!
Worf: Aye aye, captain.
Dazed-looking guy in a t-shirt, off in the corner: Whoa. Am I... Am I in space?
Et voila, a new Star Trek fan.
I'm sure he's not the only potential audience-member who is alienated by all these characters and scenarios that are somewhat different than the ones they've personally experienced. It could be a great way to access new demographics. Just write in a modern-day character and have them express confusion or amazement off to the side. Now they'll feel like they're really immersed in it!
This doesn't just have to be for science fiction, either. Just be sure to deftly include a minor character wearing jeans and a hoodie into that Tudor-era historical drama, and give them a couple of lines like, "Hey, why's everyone talking so funny?"