Source Code: Time is on his side

The Source Code is not about time travel. Or so we are told. It's about time recalibration. Whatever that is. And it has something to do with quantum physics. (Failed that in high school.) This explanation made the Movie Slut's head throb, luckily understanding how it works is not integral to enjoying this Ground Hog Dayish thriller.
Jake Gyllenhaal is in the Bill Murray role, the guy who has to do the do-overs until he gets it right. And he has only eight minutes to get it done.
The movie has it problems in the beginning, when movie-goers will surely figure out some stuff before they should, and the end, or shall we say ends, since there seemed to be three or four tacked on.
But oh, the fun, fun, fun in the middle.