Famicom Mini: Super Mario Bros.

If you ever find yourself with a Game Over, and you would like to continue from what world you were on, wait for the 1/2 Player select screen, then hold A and press Start. Now you will start at the first level of the World in which you obtained the Game Over from. For example, if you got the Game Over from 7-3, you will start over again at 7-1!

In order to get fireworks to go off after you beat a level, simply finish the level when the last number in the Time is either a 1, 3, or 6. The number of fireworks you get depends on that number. So finish a level with 106 remaining, and you'll get 6 fireworks to explode. Plus, you get bonus points for each firework that goes off.

In world 4-2 you will come across a moving platform. Jump past the platforms until you see a ledge with three blocks. Go just left of the first block and jump, you will reveal a secret block. Go over under the second block and jump (rember to leave the space under the first block empty) and jump under the third block to reveal another hidden block. Jump on top of the blocks and start destroying the blocks until you find a vine growing out one of them. Climb up the vine to reach an area with lots of coins. go right until you find some stairs. jump on top of them and walk rigth. Now you can warp to levels 6, 7, and 8.

During World 1-2, go to the end of the level and get on the rising platforms. Now jump onto the TOP of the level and go right until you reach three pipes. You can now warp to either World 2, 3 or 4.

Go to world 1-2.
At the end of the level, there is a pipe, and some bricks.
You must smash the second to last brick and the third to last brick as seen to the left.
Now you must stand on the edge of the pipe, duck, and face left
Now jump to the right towards the one block that you didn't break, while facing left
You should slide right through the bricks, go into the first pipe when you get to the other side.

You should be warped to the minus world, the level is -1.