MB, did you ever read the supposedly spoiler-heavy script "outline" that was "leaked" and then became the object of a spoiler topic here on the boards in 2011? To understate matters, the "outline" described a story that was very different from what was filmed.
I figured for some time that the "outline" was deliberate disinformation, but it occurs to me that it might have referred to an early draft of the screenplay before the Seth person was brought in to "lighten" things up more.
I hadn't even noticed the details you mentioned about the curse, the switching of dates, etc. And that's really quite bizarre abou the IMDB page for the movie.
It would seem that the narrative of the movie's development, editing, promotion, distribution, etc. has quite a few more twists and turns than what actually happens in the story the movie tells!
G.