This guide covers every collectible in the Stage Fright DLC and the only missable achievement tied to it. There are three collectibles total, each found in a different section of the DLC. If you follow along as you progress through the areas, you won’t miss any of them.
First Area
Before you reach the first collectible, there is a missable achievement called One Head A Step.
To get this achievement, you need to leave everything exactly where it originally is in the room. Do not move any of the objects around. Just proceed normally until you pick up the key. As soon as you collect the key while everything is still in its original position, the One Head A Step achievement unlocks.
After progressing through the area and solving the light puzzles, you will eventually pick up the play’s theme.
In the next section you will find a cart. Move the cart all the way around to the back near the entrance. Once it is positioned there, climb on top of it to reach the first collectible.
Second Area
In the second area you will encounter a puzzle involving Teddy.
During this puzzle, send Teddy up to the upper area. From there he can destroy the rope that is holding a wooden plank in place.
Once the rope is broken, the plank will drop down. This allows you to climb up and reach the second collectible, which is located on top of the drawers nearby.
Third Area
Later in the DLC you will meet Stage Boy again.
After you return his weapon, a collectible will appear behind you shortly afterward. Simply turn around and pick it up to obtain the third collectible.
That covers all the collectibles available in the Stage Fright DLC. There are only three in total.
Every other achievement in the DLC is story related, so as long as you complete the DLC normally, you will unlock them automatically.