I wouldnt wanna write this script...
I mean, how the fudge are they gonna squeeze all the chapters into one movie, and also have time to explain all the twists towards the end? It took the anime 25 eps to even consider explaining anything, which was just cool, creating a big twin peaks mystery of it all.
I suggest that the script writers watch Groundhog Day before they start, that similar-themed movie managed to make the script extremely thoughtout and understandable, and may actually have inspired Higurashis original story to begin with. (dont quote me on that, I dont know for certain if Groundhog Day was the first story with that "stuck in time, doing the same day over and over"-concept, but they do seem pretty similar to me).
Anyway, love the show, hope the movie doesn´t blow!