You don't think gas will ignite, pour about two gallons on the ground, stand real close and toss a lit match into it. Keep it liquid and it is harder to ignite but will if provoked enough. Put it in liquid form in a small can, barrel or what ever and you can light the top and have a nice fire, just don't kick the can or barrel over.
It will burn and can be lit with a match, if you atomize it, it can and will explode. but you are right it will not react like the movie depicts.
High octane verses low octane. The high octane fuel has a additive package that allows it to burn at a controled rate, where as the low octane fuel will explode and cause detonation in a high compression engine. One big problem with high octane gas station fuel is that fewer people buy it and it deteriorates in quality. The 87 octane fuel is moved more rapidly so is almost always fresher.