Fun fact: While shooting this scene, Peter Jackson wanted Sir Christopher Lee to scream. However, Lee corrected Jackson: "Have you any idea what kind of noise happens when somebody's snuck up on by a tree? Because I do."
The Shakespeare veteran then proceeded to give an in-depth summary of the Battle of Dunsinane.
He also did a scene where he was supposed to "scream like he'd just been stabbed" and he was like "people don't scream when they've been stabbed. They make a wet gurgling sound" and everyone had to break for the rest of the day because they forgot about all those Nazis he killed.