Interesting idea that doesn't really work so well in the form it played out. I would've enjoyed it more if it had just been a time travel story instead of the convolution this ended up being. Steins;Gate showed how time travel can work with time restraints and I don't see how that wouldn't have worked for this story either.

I really didn't understand how Gyllenhall's character couldn't understand the concept of "These people aren't real" that the people running Source Code kept telling him over and over. He even mentioned he had knowledge of simulations in the past, so it's not a completely alien idea to him. Sure, he was proven right in the end but there was nothing in the movie that implied any reason for him to believe this. I dunno, it just didn't really work for me.