Carmen Sandiego: Secret of the Stolen Drums - To defeat the bosses

For earth: keep avoiding his attacks when he bends down and his faces turn red hit his faces. When he falls apart hit nine of his minions.

For fire: between attacks stand on the aiming circle and hit the target behind his head. After he falls down keep hitting his 2nd head. All of them will eventually explode.

Bonus mode:
Successfully complete the game to unlock the "Bonus Mode" option.