It's an oft-repeated observation these days that the weird thing about the Doctor Who universe is that nobody in it's ever seen Doctor Who.
Well, I was watching Dollhouse the other day, and at one point Topher uses the expression "Frak." Which means that Battlestar Galactica exists in the Dollhouse universe. Which then begs the question of why, when meeting Paul Ballard, his first reaction isn't "Did you know you're a dead ringer for Helo Agathon?" As well as, does Buffy also exist in this universe, and if so, why Topher hasn't remarked on the strange resemblance between Echo and Faith.
A possible explanation is that only the original series of Battlestar Galactica exists in the Dollhouse universe, and thus that Topher is saying "Frack." But it's more funny the other way.