You can revisit Rocket Town anytime after you obtain the Highwind on Disc 2. Head into the Weapon Store on the left side of the screen to find a treasure chest that contains a 
Fourth Bracelet which is a very powerful piece of armor.
There is also a treasure chest in the back of the Item Store that contains a 
Guard Source.
You can also revisit Rocket Town one last time after you have retrieved the fourth and final Huge Materia after the Shinra Rocket No. 26 gets launched into outer space. Click on the link for more information about that section of the game.
Return to Rocket Town and speak to the man in front of the Item Store three times and he will reward you with the 
Venus Gospel, Cid’s Ultimate Weapon.
