I'll sum up the movie for you in any case: this professor/scientist/geeky named Alex (Guy Pearce) digs this chick named Emma and wants to marry her. After he proposes though, she gets killed by a mugger. This makes Alex pretty anti-social and he builds a time machine so he can go back and fix the mistake. When he goes back though, she just dies again. So, he travels to the future to find out why he can't change his past and while he's traveling he gets knocked out and travels like 80,000 years into the future and saves a bunch of people.

Some interesting points:

One: In 2037, someone decides to blow up the moon but they fuck it up and the moon starts crumbling and falls to the earth. Alex meets some troopers or something who tell him he has to get to his evacuation area and all the buildings are crumbled and there are these random fires. What caused this fires? Why are the buildings destroyed? The moon did not cause it and the moon wouldn't fall to the earth in any case.

Two: Alex talks to some artificial intelligence thing in the library, and in the year 80,000-whatever, he finds it again. How is this thing still running without any power?

Three: They have an area with a bunch of tiles that say stuff like "Brooklyn Bridge". I think that would fade after time.

Four: They all speak perfect English, but don't know what the word "steal" means.

Besides these lame points, Alex pretty much wipes out the cause of the future people's troubles (which mainly consist of them being hunted by these monsters who eat them) by blowing up his time machine and in one swoop, all the monsters die. I thought that he'd at least get everyone to fight for themselves or something more fulfilling, but alas. They all just kind of wait around for him outside, holding torches. What the hell?

To sum up, I quote Alyssa:

"It was the most god-awful, horrifyingly mind-numbing piece of horse crap I've ever seen in the whole of my life. It would have been better if I could have watched it with no sound, so there would have been the benefit of some kind of doubt to give it."