There are tons of glitches in sonic 3. Like when you almost let yourself drown when fighting robotnic in level 2 act 2, the music will change to the sonic and knuckles mini boss music. Also, in carnival night act 2, after knuckles turns out the lights, run to get the water shield. Then jump up so you're running on the ceiling. You should end up trapped behind a wall. And I don't know if this works for sonic 3, but it works in sonic 3 and knuckles. Go to the ice cap zoe, to the place where sonic can't get passed because it's knuckles path. Now duck until your camera goes down (by the way you have to be sonic alone) then jump. You should be behind the wall sonic couldnt go past. There are many other glitches too. See how many YOU can find.
In sonic 3, level 2, act 2, you can speed directly past robotnic while playing as super sonic. The flicky container will be all glitchy, but when you pop it, itll turn to normal. Sonic will just stand there waving his finger as if he beat the level but you will still hear robotnic blasting the bombs. Also you can not advance to the next level because robotnic is still there.
When you start go straight and turn right and at each of the corners and hit the yellow spring sphere and repeat. When you get to a place where there are no more corners go straight. There will be times that you have to jump over one and only one red sphere in you way to hit the spring sphere, jump but not to early or you might miss the blue sphere in front of you and not to late or you will have to restart the special stage. It looks hard but is truly simple. The other six sorry but I can't help you there.