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: The morning of the final battle, the sun rises behind the mission, silhouetting a sentry. When the ending credits roll, the sun sets behind the mission.
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.
Plot hole: How did Glabrus know about Silesian pirates aiding the slave army's escape? He informed the senate of this and yet was not made aware of it at the time of his capture.