I know a couple off the top of my head - (SPOILER)You can check one of the fallen guards at the train station for a Potion, there is a Phoenix Down where Biggs and Jessie open the doors for you, there is a Potion in the room where Jessie gets her foot stuck, and there is of course the Cure materia in the reactor room where you set the bomb. If you're including your escape back to Sector 7, there is also an item(I believe another Potion) in the large open area of Sector 1 where there are billboards and electricity and people running around.

But let me get this right - It's alright to actually boot up the game and play that part to get the answers if you want to?