On the "Prepare To Drop" mission , when the Carrier jumps to Slipspace Rupture, closely look at the right of the Carrier to see the Amber Clad of Commander Keyes getting into the Slipspace Rupture along with the Carrier. In Halo 2, at the end the "Metropolis" mission cinematic, you will see the Amber Clad of Commander Miranda Keyes to the right of the Carrier entering the Slipspace Rupture along with the Carrier. This is a true reference for the following reasons: in Halo 3: ODST, you are in New Mombasa and the Carrier is floating next to the space elevator. In Halo 2 you are also in New Mombasa and, at the start of the level on the bridge, you can see the space elevator and the Carrier floating next to it. In both Halo 3: ODST and Halo 2, when the Carrier jumps, there is a big EMP wave.