Factual error: The flag used when Radcliff claims the land for King James I wasn't adopted until 1801.
Factual error: The movie depicts a moose in what would be Coastal Virginia. They are not native to there at all.
Continuity mistake: When Pocahontas sees John Smith for the first time, John is climbing up a cliff face and then a tree. You can see his musket strapped to his back as he's climbing. But after he tells Thomas he's getting a better look and then is shown in the tree, his gun has vanished.
Answer: He probably knows that if he tries to escape he'll be shot down by the Powahatans' arrows. He prefers dying with some kind of dignity rather than while running.