Plot hole: When George stops the machine for the first time, the candle burned down to about half of its size, which took according to his observations 98 minutes. But as the trip continues it takes seven hours for it to burn down completely. (00:25:45)
Plot hole: In the arial shot of the plateau, it's obvious its just a mesa. It's not at all large enough to support such big animals like those dinosaurs, who would have to eat great amounts of food. All small animals would be hunted into extinction, and all of the trees would have been cleared out long ago. Plus, there would be no place for the dinosaurs to hide, so the team should have seen the monsters right away.