Continuity mistake: There wasn't much blood noticeable on the axe after it was used to chop off the mermaid's tail, but a little later when the man was carrying it over his shoulder, it was heavily covered in blood and dripping. (00:14:17)
Continuity mistake: The front view of Sheriff Garrett [Ethan Hawke] while he is talking to Billy shows a stone-walled well between him and the cabin door, but there's no well visible in the rear view. When Billy walks out with his hands up, there appears to be a well to his right (where the horse rail should be visible), but there is no well when Sara and Rio exit the cabin. (00:14:04 - 00:15:10)
Continuity mistake: When Pinky barges into the protagonist's home, multiple times (for instance when he sits in front of her) her pigtails move behind her shoulders from the front and vice versa between cuts. (00:06:00)
Continuity mistake: At the beginning of the movie, the two knights are walking across the courtyard to get on their horses. When they mention the falcons' names, a young lady wearing an orange striped cape curtsies before them in passing. A couple seconds later during the close-up of girls ogling them from distance, the same lady passes in the foreground, coming from the opposite direction and in a totally different spot. (00:00:55)