Yeah boodoo is right about the 6.5oz returnable bottles... MMMMM!
Well the 250ml can is probably just a coincidence. I'm going to assume that when the Austrian guy got back from his 6-week paid vacation to Southeast Asia and started working on the project, probably that was the size that was being produced of some sort of other stuff like SPA or whatever else, in his locale. So if the plant had been doing 12oz cans or little glass bottles he'd probably have done that instead. And actually I have a little brown returnable bottle of Red Bull but I've never opened it. I'll bet it's better than the cans...
Keep in mind that the King Of Pop\'s crown is not made from a bunch of melted aluminum cans!