Endings
There are three different endings for the game, based upon completion time.
Ending 1- Best Ending
Beat the game under 3 hours to see Samus in her bathing suit.
Ending 2- Good Ending
Beat the game under 5 hours to see Samus with her helmet off.
Ending 3- Worst Ending
Beat the game over 7 hours to see Samus give you a thumbs up.
Tricks
VAR Beam
This is one of the most famed glitch to be pulled off in Super Metroid. To do this, get all the beams and items, next on the beams section highlight the Plasma Beam, then press Left + A. This may take some time to do, but it works. When it does, all the beams should be highlighted and the word "VAR" should be above the Spazer Beam.
NOTE: If you shoot anything but a door, the game will freeze. Do this at your own risk!!
The "Reset" Glitch
In old Tourian, go to the yellow door (the shortcut room) and go in. Do the VAR Beam glitch and shoot the DOOR FIRST and turn around and shoot again. The bar on top of the screen will be glitched. Now, enter the door. Old Tourian will be all misty from the beginning of the game. Turn the VAR Beam off and go save and turn off the game. Turn on the game and select the save file you saved on. Start and the intro should start. To confirm this, watch the first cutscene. Samus should do a Screw Attack and turn into her Gravity Suit. You'll see when the game starts, the Missles are not there but the S. Missles and other items should be there. Now you can play the game again and get more Missles. Enjoy!!!