Go see this movie NOW. Holy shit is it amazing. So unique in a sea of sameness at the theaters. The vehicular choreography will blow your mind. Miller spent so much time and money building these rigs and making as much of the special effects practical special effects, it's really something to behold. This pic perfectly sums it up! So Metal! (and I don't even like Metal).
YES that guitar is an actual working guitar that really shoots flames. And none of that scene is CG. The dude trained for a month to play the Guitar Gimp alone!
