Super Mario Land

When you beat the game, press any button while you're on the title screen. The cursor will change from a mushroom to Mario's face. Press Start to play the new Expert Mode that features enemies that are more difficult, more numerous, and in different places.

Normally, during the invincibility granted by the Star, each enemy you knock off the screen will be worth 100 pts. However, when you pump a Super Ball into an enemy that is worth 400 or 800, each enemy the Star kills after that will be worth the same amount! This works with torpedoes (submarine) and missiles (airplane) as well. With enemies that require more than one projectile to be slain, one hit is still enough to get this trick to work.

If you go through stage 1-3 normally there will be coins and pipes on the top of the stage that you can't access. To access them you need to activate two secret elevators.

The first one is right at the start of the stage. Position Mario exactly three blocks away from the left side of the screen. Jump and lean against the wall and there's your first elevator. Stand ontop of the block and don't move. You will go straight through the top blocks and Mario will be on the top of the screen where your stats are.

The second elevator is at the second lion. Kill the lion and dodge the two falling stones. There will be a row of five blocks that go in a pattern of coins and bricks. Break the second brick with Super or Superball Mario. Jump through the hole you just made and the second elevator will appear. There will be no coins this time, but it will lead you to a secret pipe. In expert mode a plant enemy will be there so watch out.

In level 2-2, when you see a tall line of vertical coins near a pipe and a Nokobon, get hit so you shrink (if you're Super or Superball Mario). Ahead of you are two levels, but the lower one seems out of reach. There is an invisible floor that makes it accessible, but you must be Little Mario to walk across it.

Beat the game two times in a row, then keep pressing A. Pressing A after completing the game twice in a row activates a Stage Select. The more times you press A, the higher the stage you can go to.