Time Problem?

*Spolier*
I honestly think this movie is a good sign of what is to come from Eric Small. It presented a good, solid message in a new, if not slight odd way. I did notice something that I can't figure out. The time... Grandpa Randolph and Melanie have been there for many many years. Later we find out that Grandpa Randolph has been "away" for so long that Ryan never even knew his grandpa. So Melanie and Grandpa Randolph continue to exist in the "real world" while they also exist in the dust factory. Ryan seems to stop time when he arrives in the dust factory, and when he leaves arives at the exact moment in time in which he left... SO is it a matter of circumstance that because Ryan is drowning his decision must be instant... but doesn't that create a problem with the fact that Grandpa and Melanie could "die" on the outside, while they are alive in the dust factory... Also, I figured that the writer isn't saying there is a dust factory in literal that each of us go through, but rather in more metaphorical sense... and depending on you it would appear as everyone goes through it just in different ways. Why did grandma never arrive? If she dies instantly, wouldn't Ryan share the same fate... Also, I am sure it was by accident, because I can't seem to figure this one out. After Grandpa and Ryan come back from the mountain and walk through the closet: when Ryan leaves, Grandpa walks twoards the door that he just walked out of (the one he can't see) and looks at the calender on the door and touches it. I thought he sees the house as it was just before he developed Alzheimer's Disease... Just a few things I noticed that confused me.