There are restrooms to the right of a concession counters.
The theater room is behind the concession counters.
The stage is there inside the theater.
Backstage there are two dressing rooms, stairs that lead to the 2nd floor of the stage area and an elevator that takes the player character to the top of King Cola's Court.
The sound room is located on the 2nd floor; take the hallway to the other side of the theater past the storage room.
The top of King Cola's court is where the player will confront Oswald the Outrageous and make the decision on how to handle him. Therein is Oswald's terminal that requires Oswald's password, a cooking stove, a chemistry station and numerous radiation barrels. After confronting Oswald, there is a door that leads outside to the signal flagpole. The player character can unchain the other door by exploring the outside area.