Dog Chasing Miners
The domesticated canine is the one who is influencing - and even taming - the behavior of its masters.
Cartridge
Instead of being used to discover and mine gold, the cartridge ends up killing the yellow mongrel. So while it did not achieve its original purpose, it was still nonetheless very useful to the miners.
The Yellow Mongrel
Despite monumental, consistent attempts by the people living near the hotel (and those who frequented the hotel itself) to get rid of the cattle-dog, they could not. It was the curiosity of the dog about the cartridge, not any kind of fear or intimidation, that drew it out of the kitchen.
Miners Still Poor
What looked like a promising site for mining gold turned out to be a setback for the miners. At the end, the three bushmen were victim to the harsh realities of Australian nature - only reinforcing the reality that the hostile environment of the bush did not give up its riches easily.
