Negative World

Go to World 1-2. At the pipe that leads to the flag, break two blocks so there's one at the end touching the pipe. Now duck and jump backward toward the brick (don't break it!). You should go through the wall and pipe into a warp zone. Jump down the first pipe you see and you will be in the Negative World (-1)!

 

 

Get 99 lives to have Mario not wear his hat. If you complete a level with 99 lives, Mario will not be wearing a hat at the map screen or the next level. He will wear a hat again if his lives drop below 99.

Hatless mario

To get a mushroom house to appear in multiplayer, you simply need to clear the level when the time has the same 2 end digits next to each other when you touch the flag pole. Examples: 544, 322, 411. Depending on the two end digits, you will make different mushroom houses appear at the start point, as you would in single player when you save a Toad, only the digits are mostly red mushroom houses. Two zeros at the end will get you nothing. When you do this, you hear the original Super Mario Bros. level clear music and see a number of fireworks depending on what the last 2 digits are. 1 firework for 11, 2 for 22, and so on.

Gold Mushroom House Get Toad to the end of the level and hit flag when the last digit of the time ends in 7, 8 or 9

Red Mushroom House Get Toad to the end of the level and hit flag when the last digit of the time ends in 4, 5 or 6

Green Mushroom House Get Toad to the end of the level and hit flag when the last digit of the time ends in 0, 1, 2 or 3.