Cage plays an arms dealer in the new movie, and Niccol had to go to extremes to make sure he had authentic guns and tanks on the set.
He even had to correspond with the world's most notorious war mongerers: "It's hard to get them on the phone but I was also very surprised at how much access I had.
"All those tanks in the film are all owned by one private arms dealer in the Czech Republic. He said, 'Yeah, you can use these but I need them back by December because I'm selling them to Libya.' Those tanks are all in Libya now.
"I almost became an arms dealer. It was quite strange. All those AK47s are real and it's because it was far cheaper to get real guns than fake guns. I got 3,000 Kalashnikovs (rifles). In America I couldn't even film that scene because there would be so much of a security risk having so many real guns.
"My guy was far more efficient than my crew. When he said, 'I'll get you 50 Soviet T72 tanks and I'll have them there Monday at 8am, sure enough there they were. They were all lined up with military precision."