Flying Elephant
From Halopedia, the Halo wiki
To complete this glitch you need to go to Forge on Sandtrap. once you spawn, go into forge mode and spawn a scorpion tank. take it to one of the elephants and line the front of scorpion with the back of the elephant. go forward and if done correctly, the Scorpion will be inside the Elephant. go up and there you go! a flying elephant. you can take it all across the map. for more fun, flip it upside down and get at least 3 people on it. once everyone is one, flip it. It might kill you and them but it will count as a splatter! Try it out some time.
It is also possible to put a closed drop pod inside the control room and use it to carry the Elephant across the map, although you cannot carry it into the minefield.
Disabled
This glitch has been corrected (Auto Updates) as I have tried to do this again after I learned of it some time before and it hasnt work again(not confirmed)