Invisible Vine
Start the game on
the "springboard birds" level. Jump to the top ledge on the right and
approach the gap. Walk off the ledge and you will grab an invisible vine that
you can use to climb to the top of the screen.
Climb through the dirt
In the
"pelicans" level, position Donkey Kong Jr. directly under a dirt
section. Climb to the top of the dirt, then move him left, then right, then
left. Now move him left, right and left again and he will climb through the
dirt section.