It seemed to me that just before the screen goes to black the top was begining to totter and fail, meaning that the ending was "in reality." Yet at the same time the movie presents the question on what "is" reality. How do we know what we experience each and every day here is "real?' Hell, how many times have you woken up from a dream and could've sworn it was "real" or how many of you have memories that you're not sure are or are not dreams?
Mind-fuck of a movie and a fairly "Total Recall"-esque ending but my interpretation of the ending is that he was back in the "real world."
And, yeah, that the kids are still asking when mom will be back suggests that it hasn't been much time.
This is very true. For all we know only months had passed between the events of the movie and the events that cause Leo to go on the run.