All items of smashable foreground scenery must contain items of food such as roast chickens or cans of fizzy beverage to replenish your chosen hero..........especially if he is in a scrolling beatem-up!
When struck, enemies and especially bosses must emit audiible sounds to convey damage inflicted, or flash visibly upon being struck, most often all of the above.
If you fall in any kind of a hole, you die. However, if you jump into a tube, tunnel, or any kind of pipe, you automatically appear in another location.