Unloading a flamethrower places the liquid gasoline in your inventory (as opposed to being poured on the ground or refueling your vehicle) in the ammo category. You can then throw the gasoline like a projectile. If you light it on fire, it explodes, presumably like ammunition (haven’t tried it, but I noticed some “ammo cookoff” stuff recently in the repository). If there was a lot of gasoline, the game can freeze for several seconds, and you will get a message like “From the west you hear an explosion! x 1000.” I won’t swear to it, but I don’t think gasoline should be exploding unless it’s confined.
I just pulled and recompiled a couple minutes ago so my version is current.