Amidst the rich, detailed and gnarly mythology going on in Mad Max: Fury Road, there's one fascinating characteristic that is left unexplained in the movie -- namely, why do some of the characters spray chrome paint in their mouths? In the film this is called "shine" and it seems like the characters do it because they feel that is their key to entering Valhalla, which is like a paradise beyond the living world.

So why the chrome spray paint?

We asked George Miller about that part of the film when we sat down with him earlier this month, and he had a very specific reason behind it.

"I saw a documentary where young [Cambodian] soldiers would go into war, they had little jaded deities -- and before they ran into battle, they put them in their mouths and just held them with little straps."

At the time Miller did not reveal the documentary, but we went searching and found the 1981 Australian doc Front Line, directed by David Bradbury. Watch the trailer below, and in a couple of scenes you can just about make out the tiny Buddhas hanging out of the soldiers' mouths.

Here's a description of the film via a forum:

“'Frontline' By David Bradbury is a worthwhile DVD combat documentary mostly focused on the dieing days of Cambodia. Cameraman was Neil Davis who was later killed in 1985 Bangkok coup. Footage is absolute frontline combat, Cambodian troops with Buddhas in their mouths as they throw grenades and move against dug in NVA and KR. Probably the most extreme combat documentary from the Vietnam/Cambodia period. He films a couple of his friends dieing, one a Cambodian photographer shot through the throat and left behind as the KR overrun their position.”

Miller went on to add that this film -- nominated for an Oscar for Best Documentary -- was his inspiration behind why the War Boys were spraying their mouths with chrome paint. This was their ritual before battle -- that, like the Buddha, the chrome paint will help lift them to a higher place. It'll help bring them to Valhalla.

Hopefully knowing that adds another wild element to your experience of the film and of the world crafted from the mind of George Miller.