Previously in Halo 2, if one were to change their date and clock on their console, one would find different signs for each date replacing the original "No Swimming signs" in Zanzibar. The same can be achieved on Valhalla, which has different messages located on the Forerunner Wall. These notes will not appear if you are on split screen.
These can be accessed simply by changing the date on your Xbox 360.
- January 1 (New Year's Day): Make Love Not War
- April 22 (Earth Day): A skull with a recycling sign.
- May 5 (Cinco De Mayo): Toady Was Live!
- July 4: BBQ at Bob's Place (this is a reference to Marathon in which you kill BOBs or BOB-B-Qing).
- July 7 (Bungie Day): Seventh Column Symbol.
- October 31 (Halloween): A grave stone that has the initials "R.I.P.", meaning "Rest In Peace".
- November 11 (Veteran's Day): Kilroy Was Here. (Reference to a doodle that became popular in the WW-II era)
- December 25 (Christmas): A Christmas light with an X on it.