Unintentional comedy
Maybe it's just me, but the scene where the enemy tries to storm the castle with this huge make-shift tower on wheels cracked me up. Maybe it was the timimg or the set-up. Heston and his crew are in the castle and they hear the sound of chopping wood and they wonder whay they're up to. And suddenly this rickety montrosity on squeaky wheels advances slowly up the road. Am I the only one who thought this was funny?
There is no "off" position on the genius switch.