Goofs

Shortly before the dragon lands, Kate approaches with a white horse but in the next shot she binds a brown horse to a tree.

When Will brings Kate back to the castle after she ran away, the clothes she's wearing keep changing depending on the camera angle during the horse ride: sometimes she has a cloak, sometimes she doesn't, sometimes she's wearing small black shoes, sometimes she's wearing brown boots.

During the long scene in which Will's father is killed by the dragon, it is raining and both Will and his father are noticeably dry throughout this scene.