In the movie Source Code, during one of his "flashbacks," Stevens experiences the world appear to disintegrate, and "digitize." While watching the movie, you get the impression this is the result of a flaw/bug/glitch/whatever in the Source Code program.
But by the end of the movie we learn that the "flashbacks" were reality in an alternate timeline/universe
so it could not have been a simple glitch in the recreation of the flashback. What explains this disintegration/digitization effect he experienced?