Plot hole: Isn't it rather strange that nobody outside the Howard family's small town expresses any interest in the confirmed discovery of a new human sub-species, the only one on the planet? Wouldn't it be more likely that their little backwater town would be inundated with every press and scientific organisation on earth, and that the Howard family would be the centre of the greatest publicity carnival of all time?
Continuity mistake: When the evil spell takes over the tree in the Forest of Feelings, Brave Heart Lion has his symbol on his belly in the shot as Swift Heart rabbit is coming to the rescue. They don't get their symbols until the end of the movie. (00:41:05)
Other mistake: Just after Isabeau falls from the abbey tower and turns into Ladyhawke, a soldier emerges onto the roof of the tower and questions Phillipe. An arrow is then fired (by Navarre) into the left-side of the soldier. However, he initially grabs at his right-side. After a couple of seconds he correctly grabs at his left-side, before falling off the tower. (01:00:26)
Revealing mistake: When Lowry first arrives at Buttle's flat to return the cheque, he hears a cough and turns to see a man smoking a cigarette, half hidden by a column. When he blows a cloud of smoke it is easy to see that it comes from a tube next to his mouth. He isn't even exhaling at the time.
Continuity mistake: When Cornelia leaves some food and a can of soda out for Joe, the label says "Coke." In the next shot, when Joe goes to get the meal, the label on the can is "Coca-Cola."