And the dream time dilation is not a real thing, dreams actually occur in real time, and the entire premise of the movie relies on that conceit. So those were always in the back of my mind.
...but a dream that can seem to last hours occurs in seconds of real time. The movie got that right.
No, it didn't.
Most studies show that when REM dreamers are awakened 5-15 minutes after the beginning of REM and asked to decide on the basis of the duration of the events in their dreams how long they had been dreaming, almost 90% of the time the subjects answered correctly between 5-15 minutes.