Okay, to be frank with you, the Hidden Palace zone does NOT have two acts! (It only has 1) So, here is the picture of 'act 1' of Hidden Palace.

After winning in Lava Reef, you will run all the way towards the Hidden Palace. Note that Knuckles enters it a little differently ( He doesn't need to fight the boss of Lava Reef act 2 ).

and fall

and fall

If you like VS ( versus ) fighting games, you'll love this stage ( unless of course you use Knuckles ). In this stage, if you are Sonic, you have to battle Knuckles. Knuckles can do everything that you can do, however, he can do more ---- Punch, glide. Well, if you look at it now, you'll thing that this will be a very difficult stage to pass! Surprise, you're wrong. No, I'm not joking. It really is easy, and fun too! Also, there are no badniks here. When you defeat Knuckles, Robotnik will come along and steal the master emerald from the Hidden Palace. Knuckles gets up and chases Robotnik. False move, Robotnik takes out two 'pincers' and gives Knuckles a nice electric shock. Robotnik now makes his hasty escape.........
The tips have rather alot of pictures, you have to come to this page to view them.
Midi file for Hidden Palace (It is the same as Lava Reef act 2).