The Ray Bradbury short story "A Sound of Thunder," an unnerving morality tale about modern man's arrogant disregard for nature, ends with time-traveling dinosaur hunters returning to the future to discover that by stepping on a single butterfly, they've altered history inexorably. The hunters become trapped in an alien world of their own making.

But the new movie "A Sound of Thunder" not only misses Bradbury's point entirely -- using his ending as a jumping-off point for an action-adventure attempt to fix the hunters' mistake -- it's also a catastrophe of bad acting, ludicrous science and conspicuously cheap special effects that can't even follow its own internal logic from one scene to the next.

Stoic, beer-and-cigarettes guy's guy Edward Burns ("15 Minutes") is unconvincing as a genetic scientist and utterly bland as an action hero who leads the hunting exhibitions for wealthy thrill-seekers to fund his research on wildlife cloning.

The time-travel contraption he uses -- apparently powered by flashing lights, dry ice and steam vents -- is supposed to be full of fail-safes, but the amoral, corner-cutting businessman who runs the safari company (Ben Kingsley, looking downright embarrassed) has shut them off to save money. After an expedition to the Cretaceous period goes awry, with that butterfly being smushed when the hunters run from an allosaurus that looks like a giant plastic toy, the movie's preposterous plot begins unraveling almost immediately.

According to the utterly nonsensical script, the changes the hunters effect in the timeline happen in 24-hour waves -- yet if Burns can put things right in the past, everything will go back to normal all at once. On their first day back, killer tropical plants start taking over Chicago and all the power goes out (there's never any mention of how the rest of the world is affected). Next, killer half-reptile, half-mammal gorilla-sauruses start taking over the decaying city and eating its residents (apparently the hunters somehow prevented several ice ages and the demise of the dinosaurs too).

According to the time-machine's bitter inventor (Catherine McCormack) -- who, of course, tried to warn everyone this kind of thing could happen if her device was usurped for tourism -- human evolution won't be affected until the last wave because "we were the last creatures to evolve."

Even without the mind-boggling scientific ignorance of that conceit, this debacle of a movie is layered in the kind of idiocy and ineptitude that seems to be the raison d'etre of director Peter Hyams ("The Relic," "End of Days," "The Musketeer").

The sound effects are unintentionally funny (army boots walking on a liquidy surface make a clank-clank-clank sound), and the visuals effects even more so. In several scenes the actors walk in place on a soundstage while chintzy blue-screen backdrops move behind them so unconvincingly that it's hard to focus on their endlessly prattling exposition. And the characters are often off-the-charts stupid. When Burns and his team review a recording of their botched mission trying to figure out what they need to fix to put the world right again, they actually fast-forward through the parts that bore them.

Even when McCormack finally does find a way to send Burns back into the past to save the future, their plan doesn't gibe with the fabricated rules of temporal physics laid out earlier in the movie.

These problems and the picture's endless parade of insipid clichés (a sassy computer called TAMI, an expendable cast member who sacrifices himself to save the stars from a gorilla-saur attack) might not matter so much if "A Sound of Thunder" was amusingly bad science fiction, like, say, "Battlefield Earth" or an Ed Wood movie. But there's no camp value here (save those chuckle-worth special effects), just repeated slaps in the face to Bradbury's source material and the common sense of the audience.