Super Mario Bros. Cheats
Continue game play
Hold A at the game over screen. While keeping that button held, press Start when the title screen appears. Alternatively, hold A and press Start(2) at the title screen.
Hit the flagpole at the end of a level when the last digit of the timer is 1, 3, or 6.
Stand on top of the exit pipe on world 1-2 and scroll the screen as far right as possible. Run to the right, then back to the left as far as the end of the pipe, then back again several times. The screen to reveal a blank space on the far right side of the bricks. Jump up and break the only second and third bricks from the right. Place Mario on the pipe with one foot off the edge and face him to the left. Press A to jump, and press Right while he is in the air. Do not break the remaining brick. The back of Mario's head should hit the brick and pull him in. Walk through the bricks to the right and immediately enter the first pipe on the left.