Black Hole
To enter the black hole, a secret area on the map with no apparent way in, you must enter Level 1-2 (Asteroid Belt) and keep going until you find a spinning asteroid bar. Hit the center of the asteroid bar just before you hit it. Do it with the next 2. If you hit all three bars right before you hit them (fly through where the breakable asteroid was....) A Laughing asteroid will appear. Shoot it repeatedly to open the gateway to the Black Hole. There are three level warps in the Black Hole. Fly through and look around this Lost ship graveyard...
Enter another dimension
Choose level three, then go to the asteroid belt and keep shooting the second big asteroid until it is destroyed. A bird-like object will fly out. Do not shoot it. Ram into it to travel 'out of this dimension'. Shoot the paper-like objects. The boss does not have a life meter, just icons (until they display three 7s) Shoot 'THE END' letters until they are in the right position. The letters will be orange when they are correct.
Star fox hidden song
After beating the game on any of the difficulty types, wait 10-20 minutes on the THE END screen and a clip of a secret song that never was played in the game will start it will repeat about five times until stops completely.