Plot hole: When Tails is flying towards Prison Island for the first time, he spots Amy on the island surrounded by enemies after mistaking Shadow for Sonic. There is no explanation given for how Amy arrives on such a guarded and fortified island. When Sonic asks her later, she says that she hitched a ride with Tails in his plane, but she couldn't have, as Tails spotted her on the island as he was flying in.
Bug: In one or more of the water races for the Chao, there are some large red crabs moving back and forth on the side lines. When they move to the left or right, their claws raise up, and then they lower the claws. But as soon as the claws lower, they instantly vanish and reappear above them again and lowering once more.Quantom X