In one scene, a young soldier describes William Wallace (Braveheart) as being 7 feet tall, yet Mel Gibson (who plays Braveheart) is only 5'9" tall. The movie also hints at Braveheart's giant sword. The real Braveheart was believed to have been 6'7" tall and had a sword that was roughly 5'4" long.
Historical inaccuracies are not slip ups! Calling this a slip up means you expect that all historical characters must only be portrayed by actors of the same height, weight, build, hair color, eye color, skin complextion, age, etc.