I have a bit of a thing about bad time travel stories. Essentially, if your own version of time travel is generating paradoxes, You're Doing It Wrong. There are only two ways of not generating a paradox: either you subscibe to the Einsteinian, 'all events are already embedded in the structure of spacetime' view (e.g. Twelve Monkeys, Bill and Ted's Excellent Adventure, etc), and you have a timeline that is already fixed - past, present, and future - so you can't affect your own past, as it has already happened, and if you try, you'll find out it didn't work for some reason. Or, you go via the quantum physics angle and have multiple parallel worlds/timestreams (Donnie Darko - mostly, and with added mystical bullshit, more more especially the excellent Primer), where the act of time travelling simply propels you into a parallel timestream, so you can affect the new timestream, but - crucially - not the one you came from, and therefore not your own past. There is no other self consistent way of doing it. Sorry, but that's just the way it is. It's just physics.
The most recent example of this, and the one that annoyed me enough to make this blog post, was Looper, which thinks it's really clever, like Inception, but which is basically really stupid, like Terminator. Spoilers follow.
Let's ignore the ridiculousness of the Premise (mobsters in 2074 have access to "underground" time travel technology and use it to dispose of corpses because it's too hard to do that in 2074 - WHAT??) - even swallowing that piece of shit (which is then utterly disproved within the movie by the version of 2074 that we are shown), there is the whole question of how they go about it. Much of the film behaves as though it's Einsteinian, with self-consistent time loops - hence the name. But then, when someone is tortured in 2044, the 2074 version of THE SAME PERSON suddenly finds his fingers disappearing. Er... surely that 'happened' to that character 30 years ago, and he'd already be aware of that?
It's almost - but not quite - as bad as the worst example I can think of: the Kris Kristofferson movie Millennium, where changing things in our present causes things to change in the future, but the propogation of these effects somehow takes a fixed amount of (subjective) time in our timeline. Er, no - for our future these things surely already happened decades ago? Another corker is Star Trek: Generations, which tries to inject some tension by having Kirk and Picard in a 'race against time'. But hang on - a 'race against time' in a movie where you can time travel at will? How the heck does that work? Surely if you mess it up, you can just travel back to before the event and have another go? Jeopardy? What jeopardy? The logical inconsistencies of the Terminator series would require an entire essay. In Back to the Future there's a sort-of half hearted nod at multiple parallel worlds, but somehow, and conveniently for the purposes of the plot, people's memories are able to transcend switching timelines and remember the old, vanished timeline, even though those events NO LONGER HAPPENED. I won't even mention Dr Who. I like Dr Who, but... let's just not go there.
Time travel is just something that stories and movies tend to do really badly. So much so that it actually makes me want to write a self consistent multiple parallel worlds time travel story. In fact, I've already started. Or perhaps I've already finished...