The scenery is meant to repeat out in the desert. It's that Flintstones-style effect for suggesting that you're travelling along in the same terrain, without having to draw hundreds of slightly different pictures of sand and rocks. Actually, back before you leave the prison... there's the gate you went out through, but off to the right, there's a shaft of sunlight glaring down on the right-hand side of the screen. Go through the 'hidden' exit there, I think it's a slightly quicker road to the Boss.

...by the way, why is this thread called 'Part 1'?