Get fireworks at the end of a level:
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.
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.