Elephant flipping

Although the Elephant is the only indestructible human land vehicle in Halo 3, it is possible to flip an Elephant over, unlocking an interesting and somewhat funny Easter Egg. Also, if you put Reciever Nodes on the surface of a flipped Elephant, it is possible to launch vehicles out of the map if placed correctly under the Elephant.

Gravity Lift Method
The easiest way to flip an Elephant is to spawn a closed drop pod in the cockpit and throw down a gravity lift right near it.

Fusion Coil Method
Firstly, go into Forge mode and put all the Fusion Coils and Plasma Batteries on the back of the Elephant. Then set the Plasma Batteries and Fusion Coils settings so every number is the highest possible. Then stand back and shoot one of the Fusion Coils and wait until the Elephant lands.

Scorpion Method
It is also possible to use a Scorpion to flip the Elephant. In Forge, spawn a Scorpion and move it to the rear of the Elephant. While in Monitor mode, hover the Scorpion in the back of the Elephant wedging it between the floor and the walkways on the second level. Once the Scorpion is wedged in tightly, pull back as if to move it, if wedged in enough, the Elephant will be able to be raised off the ground. While in the air, rotate the Elephant using the controls to flip.

Run over Method
Another way of flipping an Elephant is to drive one towards and partially over the other, then get out and drive the other one forward until it flips it over. This is the only way to flip the Elephant that you don't have to go into forge mode to do.

Forge and Drop Pod
Go into Forge and place a drop pod. Take the drop pod and put it inside the cockpit and fly up. The Elephant will either fly up in the air, or the drop pod will slip out and you will have to do this again.