Same as people I've seen comment, "Well...how can they be brother and sister if he's black, huh!?" Are there that many morons who have never heard of adoption?They switched it to them going to another dimension. They probably figured that a green landscape would be more alien and jarring than a red one. People read so much into these things, I swear.
I mean, yeah, that's a pretty noticeable colour palette change between trailers and the "alien landscape" is a pretty good explanation, but how hard would it be to figure out adoption?