Lone Wolf Spartan Statue glitch
From Halopedia, the Halo wiki
After playing the level Lone Wolf, go to Theater mode and pause the camera a few seconds into the level. Then, rewind to the very beginning of the clip and detach the camera. You should now see a large segment of the Asźod yards, which form the background in the actual level.
Zoom over to the shipyards, and in between the two yellow cranes is a tiny Spartan model.