I'm a little lost; I love the story and the idea, but you've basically jumped from the beginning to the beginning of the end. Is the rest of the story going to jump around like this, or are you going to back up and explain what's happening? Great chapter though!

I have to wonder: if Anna is a genius inventor and she considers her sister to be the brains of the family, what does that make Elsa?

I think that this is a pretty cool, but surprising idea. Switching Anna with Steve Rogers? Surprisingly workable, as they're both earnest people with a strong sense of right and wrong. Switching Anna with TONY STARK on the other hand, there's a fair amount of contrast between the characters. Still, due to the contrast this should be interesting.
Have to admit, I had a bit of hope that this would tie into Frozen: Winter Soldier because, since you swapped Black Widow for Flynn Rider/Eugene from Tangled, we'd see more swaps in that verse. Still interested in this, don't get me wrong, so if there's supposed to be more I'm interested.

Hehe, this is really nice. I like how Anna is so calm about the whole thing.

This sounds cool1