!! '''The bosses of the four selectable levels were based off the [[ClassicalElements four classic Greek elements]] (Earth, Fire, Air, Water)'''
There's four of them, and they have traits which can roughly be tied to one of those four elements at that.
* Desolation Canyon -- Fire (Grand Dragon -- a tank that attacks with a flamethrower and incendiary missiles)
* Gold Mine -- Water (Giant Crab -- a GiantEnemyCrab, and is thus modeled after a water-based creature)
* Armoured Train -- Air (Flash Boy -- a guy on a jetpack, who obviously flies through the air)
* Ammunition Depot -- Earth (Geas Crystal -- a snakelike robot which essentially has a giant gemstone over its core)
* The remake in ''Wild Guns Reloaded'' adds one more in Underground -- Lightning (the boss has an electrical attack from its horns)