Mongoose glitch
From Halopedia, the Halo wiki
In forge mode on High Ground grab a mongoose and take it to the beach. Have somone get on and then a second person get on passenger. Have the driver get off but the passenger stay on. Have another person go into forge mode, pick up the mongoose, and by using RT and the left stick push the mongoose outsite of the map. The passenger can then get off and he will be outside of the map.
