[[WMG: Johnny is perfectly innocent.]]
We never see him perform any of his crimes, he's only left there at the end of the rape scene. He's thought of as a wimp by the rest of the gang. He visibly refuses to burn Goose alive. And, of course, he may have just found the truck destroyed and needed shoes.
* But we do, however, see him messing around with Goose's bike which causes the crash (though what he did to make the brakes lock up at speed is never explained).
** He loosened the rear axle, and it caused the wheel to lock up, probably when the bearings jammed.

[[WMG: Lord Humungus is actually Fifi]]

Think about it. He wants to bring heroes back to Austrailia. What better way to do it than be the Villain.
* Plus, Fifi was a pretty big guy, as was Humungus.

[[WMG: Mad Max is set in the ''VideoGame/{{Fallout}}'' universe.]]
Australia was physically mostly untouched by the bombs but society broke down just like everywhere else.
* Yet their cars are all modern vehicles and transistors are widely used, whereas Fallout has wide use of vacuum tubes because the transistor wasn't invented until just before the war, and all cars look like either generic postwar era vehicles or the Ford Nucleon concept car.
** Unless America was somehow technologically backwards in the ''Fallout''-verse? Combined with the '50s cultural stasis, maybe there was technological stasis too, and the US was enough of an industrial powerhouse to be resistant to competition from better foreign tech?
*** Wouldn't work. Fallout had AIs, Computers, Robots, Both big and small, laser weapons, plenty of ammo. So did China. China had energy guns themselves, and fully working stealth suits. Australia had to have had something.

[[WMG: The fluid they are obsessing about in the movie (Mad Max 2, at least) is water, not petrol]]
While the film does mention "Guzzoline" a few times, they never actually state the stuff they're pumping is fuel. Also, crude oil requires massive equipment to fraction into burnable fuel, which they simply don't possess there. In the field, you don't see anyone pouring their collections into a car. Water would be precious in a desert environment, and would be a reason for Humungus to attack. If they needed fuel, why were they so profligate with their consumption?