Agency

Clearly marked with their signature logo with AGENCY written on it, it's clear agents would communicate with notes mostly hidden.

Hotel from the Future: Closet

Steps:

1. Go to the hotel and grab a room.
2. The note is hidden on the top of the closet. You can jump into the closet to see this note.

Hotel from the Future: Chair

While this note doesn't have an Agency stamp on it, it's been widely accepted by the community as a secret message by the Agency.

Steps:

1. Go to the hotel and grab a room.
2. Sit on the White Chair on the left when facing the Window or go behind the Chair

Quantum Room

Steps:

1. After spawning the 7 carbon blocks, head to the secret X-Ray Room in the Hospital. Look Underneath the Table and Click the blue Button to get inside the Quantum room.
2. Dive underneath the Water and see this note on one of the stools.

Experimentation Site

Steps:

1. Go to the hidden XRay Room in the Hospital
   1. Click on the Scalpel behind the false wall in the Xray Room behind the cabinet.
2. At Agency Experimentation Site (Second Floor of the Hospital)
   1. Click on the Button found under the Surgery Table to turn the lights on
   2. Sit in the chair on the right under “Experimental” and get slimed!
3. Look behind one of the chairs in the Agency Experimentation Site