Bear Grylls from "Man vs Wild" on Discovery Channel is lost in the Costa Rican Rainforest. He comes in via parachute and lands in the tree tops. This is how you get down if you should get stuck there.
If you're lost in the African Savannah, you will need to follow a stream back to its source rather than down stream where it eventually will just disappear.
Bear Grylls is in Mexico, and finds a cave that has been used by the Rarmuri people. There are signs of humans and he even finds a useful piece of wire.