Just something cool I found and thought you guys should know:
On the forge map Ravine:
Spawn the Terrain piece Artifact Base [Can be found in the Ravine structure section of the menu for those who don’t know].
In the reflection you can see sections of the Halo 3 Campaign levels Tsarvo Highway, Crows nest and The Storm
Note:Can also bee seen in the reflection on some parts of the main structure
Pretty cool little Easter egg