Throughout the game, extensions have been found. These may or may not relate to the ARG. This is a list of extensions found on whiteboards
- JD Marcel -- Ext. 1187 - 463 (although it's been mentioned that is a reference to the 90's tv show "Bugs")
- Dr. Foreman -- Ext. 384
- Dr. Horn -- Ext. 186759
- Anomalous Materials -- Ext. 01(4,6)33
- Ext. 3914 - The Ext. requested by Victor in Code C.
The significance of these extensions are debatable, and nothing has been confirmed regarding their relevance thus far.