I watched the trailer. The first thing I thought after I saw the other Earth in the sky next to the moon: "Uh oh. Is that going to screw up the orbits of the planets and kill everyone??"
Trailer's pretty vague, but that shot of the sky was pretty awesome.
Wonder if they'll address changes in the tides at all....
Well, Source Code was (a greatly enjoyable) mumbo-jumbo as far as science is concerned, but I think they were playing with MWI-type ideas.
More like "if you run a computer simulation, the simulated world keeps existing after you turn off the simulator". It might help us get to the future by breaking some future shock, but it's not a meme we want to take with us when we get there.
Another Earth: Trailer.
Thought some might find this interesting.