^ They did grow old in limbo but showing that they were young during the train track scene shows the realization that they were in a dream. Also about the ending, Michael Caine, Leonardo DiCaprio's father-in-law in the movie, stated in an interview that the spinning top did fall in the end of the movie and it was intended by the director as well.
Caine is quoted saying, "The spinning top drops at the end, that's when I come back on. If I'm there it's real, because I'm never in the dream. I'm the guy who invented the dream."Link
So there you have it, whether its true or not I still like to see the ending of the movie as an interpretive ending.
Caine is quoted saying, "The spinning top drops at the end, that's when I come back on. If I'm there it's real, because I'm never in the dream. I'm the guy who invented the dream."Link
So there you have it, whether its true or not I still like to see the ending of the movie as an interpretive ending.