In the behind-the-scenes featurette produced for the film’s DVD release, special effects supervisor Michael Lanieri discussed the logistics of staging the Flesh Fair, where mechas are destroyed for the enjoyment of human spectators, in as practical a manner as possible (i.e. with only as many CG elements as necessary). In retrospect, he wonders if he might’ve gotten a tad carried away when he suggested to Spielberg that they could go totally live action with one complicated bit.
According to Lanieri:
“Steven came up with this idea that we would have a couple of cannons, and we had much like a ring, like a coliseum affair, if you will, and out of the cannons have to shoot two people, who travel 50 yards, who go through a ring, who catch on fire, and then hit twelve-foot spinning metal blades, bust up into pieces, and land onstage where this heavy metal group, Ministry, is playing.”
When Spielberg signed off on the idea, the great makeup f/x artist and creature constructor Stan Winston whipped up a couple of mechas for Lanieri and his crew to burn up and shred. Be careful what you ask for.