Yup. At one point in the movie, Pinkie comments that there's a girl that looks ALOT like Twilight, who also has a dog named Spike.

Well, I guess that's one thing I can give credit before going to the theater this weekend, It doesn't just say "Cause Magic" it actually gives a reason, though I hope it isn't like a one sentence explanation of The original "Human" Twilight disappearance.