I watched Deja Vu again the other night. First time I saw it three years ago I was gripped by the tension and the excitement of the movie. Any flaws in the plot passed me by. This time, however, I was aware of things that didn't gel, not in the least by the fact that my younger son insisted at one point in stopping the video and explaining why such and such a thing couldn't have happened, even given the logistics of the storyline.
Well, that's the way it goes. You have to be very careful when you're plotting a movie that plays around with time (Back to the Future manages to get it right pretty much all the time). Put a couple of things out of their possible sequence (even given the state of time travel) and the audience will start quibbling. My son was most concerned about a phone call that couldn't have come about because the girl was dead at the time she was supposed to have made it. And if you look on imdb.com, you'll find dozens of other goof-spotters who are equally concerned about things that aren't quite according to Hoyle.
Nevertheless, Denzel Washington pretty much saves the day. His gradual falling-in-love with a girl he knows to be dead (via images of her from four days before) is wonderfully done. Val Kilmer gets almost nothing to do, but carries off a dull role with as much oomph as possible. James Caviezel doesn't make a real appearance until well into the movie (we've only glimpsed him very early in the piece) but when he does actually get to play his scenes, the intensity level increases enormously. He doesn't get enough decent screen roles, really. Paula Patton is just gorgeous.