mario original glitches

• Unlimited 1-Ups

  Get to world 3-1, and become Super Mario. At the end of the level(the staircase before the end flag) you will see two turtles coming down the stairs, jump over the first one and then jump on the second one. It should hit the star and bounce back, from here jump on it and keep yourself up, after a certain number of bounces without hitting the ground, each consecutive bounce will get you a 1-up. Get as many as you want but be warned, if you get over 100 you will get a Game Over.
  

• 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)!
  

• Shoot fireballs as small Mario

  Go to either 1-4, 2-4,3-4, etc. and get to Bowswer. Make sure you are Big Mario and try to jump over Bowser or run under him. Stand near the Axe and Bowser will start to walk towards you. As he gets near you, jump high, and touch Bowser and the Axe at the same time. If you do it correctly, you will hear the sound as if you were to shrink, but you will just flash and stay big. Go to the next stage, and get a Mushroom. (Yes, there will be a Mushroom instead of a Fire Flower.) When you touch the Mushroom, you will shrink. Then get a Fire Flower, and you'll have Fire Power as small Mario. (Note: after you do the Bowser/Axe trick, enemies that touch you will be able to kill you when you are Big Mario. When they touch you while you are small Mario after getting the Mushroom or Fire Flower, you will turn back into Big Mario.)
  

• Access 5-1 from 1-2

  To access this warp, you must be Super or Fiery Mario. Go to the pipe at the end of the level and jump on top of it. Jump up and break the block over top of the part of the pipe farthest left. Then, position Mario on the edge of the pipe, with one foot hanging off the edge. Duck, then jump backwards as far right as possible. If done just right, Mario will slide through the pipe and the bricks. Walk over to the warp zone area and enter the middle pipe. This pipe will take you to world 5, level 1. The same area can be acessed from a pipe in the same place in 4-2. However, this is meant to be a warp zone to 5-1, whereas the 1-2 warp to 5-1 is a glitch. After completing the jump trick in level 1-2, you can also go down either of the other two pipes, both of which will take you to Minus World -1.