A Sound of Thunder

Based on a Ray Bradbury short story A Sound of Thunder is another case of a movie delayed in its release because of production problems, in this case over 2 years, as it was going to be originally released in 2003. But I know that the problems did not affect the writing of the movie by Thomas Dean Donnelly, Joshua Oppenheimer and Gregory Poirier, nor the direction by Peter Hyams or special effects (which deserve a whole paragraph just for them), all horrible.

Edward Burns stars as Travis Ryer as the leader of a hunting group sent to the prehistoric era where dinosaurs ruled the rule. It's all part of a Time Traveling Safari, which company owner Charles Hatton (Sir Ben Kingsley) offers to the most rich people in the world.
But there's Sonia Rand (Catherine McCormack), the woman who invented the technology, who warns them that what they do is wrong because just a little mistake (known as the Butterfly Effect) could be fatal as just by killing a butterfly in the distant past you could modify the evolution of the species, all the species. And so of course it happens, and the writers wouldn't think of anything original so they went with the laziest idea, they accidentally kill a butterfly while on a trip, and monstrous beasts suddenly appear out of nowhere in the world of today killing all humans. The world of today in the movie is in the future too, though it looks just like our time only that the cars are computerized.

The special effects are some of the worst I've ever seen. Starting with the aforementioned cars which look straight out of an old videogame. And the city is a disaster too. It's so obvious that you can clearly see the actors are walking on a machine in front of a camera. Then the Monkeysaurs and the huge bats (or at least they looked like bats) are the only 2 monsters the filmmakers could come up with. And they are horrible.
Same for the T-Rex they go to kill when they go back in time. It looks extremely fake and the effects of the ice-shots hitting him are horrible.

Other than Burns, the rest of the cast are pretty bad in the acting department (Kingsley is embarrassing), and for a time traveling movie, the story doesn't explain much of what's going on, including waves of energy that appear every couple of hours to change the evolution of things. It's explained all very quickly and it makes no sense.
The studio waited 2 years to dump this movie in not many theatres and on this time of year when all the bad movies that are sure to fail get released, and A Sound of Thunder won't be an exception to that.