In the level Armory, the player can find many hidden messages. Here are some of them:
- On maybe every control panel in the armory, there is at least one screen with a message:
CODED MESSAGE:WU 1120 REJECTED BY ADMINISTRATOR REV. PAIN MAY CONTAIN HARMFUL CONTENT. RESULTANT PSYCHOLOGICAL DAMAGE ACTION: CENSORED
- On the Control Panel in the corner of the room, behind the armor plates, there is two lines of ten blinking lamps. Over and between them is some really small text. On the top of the first line the message says "FUSION GRID STATUS" and on top of the second line it says "BLINKING LIGHT SIMULATOR".
- On the floor in the shield tester is a warning: "Warning! Unauthorized personnel must stand clear".
- To the right of the elevator is a pile of boxes. One of them contains the deadly VX 7 Nerve Gas.
- If you look at the different boxes you can find some interesting items, like Marine Boots, the mobile turret that Sgt. Johnson carries at the start of the "Cairo Station" before the "Home Field Advantage" part. There are even some funny meals.
- "Rev. Pain" is the player name for one of Halo's creators from Bungie studios.