I've a question re: The "Dream Time Dilation."
During Ariadne's training, Arthur explained that 5 minutes in the real world feels like an hour in a dream, which is a factor of 12.
Later, Yusuf explains that the sedative used in the mission slows time by a factor of 20. So the 10-hour flight would take 200 hours, or over a week, in the first dream.
The "normal" factor of 12 would cause the flight to take 2400 hours, or three and a half months, in the second dream.
The third dream added another factor of 12 to make the flight take over three years.
Time seems to move even slower in limbo, but it's not clear how slowly, because the same rules don't seem to apply there.
I think the movie did a good job of portraying the time dilation, though of course the time doesn't match perfectly. During the ending sequence, they showed the scenes of the van falling in dream 1 in slow motion.
In dream 2, the scenes of Arthur rigging the elevator were at regular speed, but not much happened while we weren't watching; whenever we returned to a scene with Arthur, it seemed that very little time had passed.
Dream 3 was also at regular speed, but whenever we returned to a scene there, it was usually implied that we missed a few minutes of traveling or fighting time.
If you were to add up the time the movie spends on each dream, it probably wouldn't come very close to fitting the "factor of 12" rule. However, I think the movie did a reasonable job of conveying the idea that time moved more slowly each time the characters went to a deeper level.