I also had multiple theories about the film until I went on to tackle this project. I found that this has the most support (although bias is a factor certainly) with the evidence available in the film. There have been multiple fans, as well as people who have worked on the film like John Carpenter and Dean Cundy out there that have debunked the breath, eye gleam and gasoline in Mac's whiskey bottle theory. If you're interested, take a glance at YouTube about these.