Wonder Boy in Monster Land/Round 4

As you head from right to left, some of the platforms will release hidden bags of gold. The platform moving up and down also has a bag as well, although you have to jump when it is at its highest.

A hidden 5G coin is at the palm tree, and another 15G bag is a jump from the horizontal platform.

When you reach town, jump at the edge of the series of buildings for some gold.

Boss
The boss at the end of the world is a blue octopus. It launches a fan of five bullets into the air, which then descend.