Factual error: When Carl first receives 26 at the hatchery, he asks what kind of dinosaur she is. He is told she is a Hadrosaur (duck-billed dinosaur), but when we see her, she is some sort of Ceratopsian (i.e.: Triceratops). She is later referred to as a Chasmosaur (which while not looking like 26, IS a Ceratopsian).
Plot hole: The dinotopian island is so large that there are mountain ranges, massive rivers, and whole towns so far apart that it takes days to travel between them. Yet this island is also so close to the mainland that they stumble upon it with a single engine propeller driven airplane. Such a land mass would be just a little hard to miss.