There are two additional difficulty modes hidden in Mega Man 64. To unlock Hard Mode, you need to finish the whole game. Don't turn off the console. After you have watched the ending, start a new game. You will now have the option to play the game on Hard.

To get the utterly superfluous Easy Mode, you have to finish Mega Man 64 in under 3 hours of total play time (yes, the game is really that short) or, if you've unlocked it, finish the game in Hard Mode. Why would you need Easy Mode after finishing the game on harder difficulties? Beats us!

In the shopping arcade outside of town, if you kick the pop can into Jetlag Bakery you will get 1000 zenny instantly.