The DJI Go mobile app is only able to show one camera on screen at a time. Either the Zenmuse or the Double 4K.
It should be noted that each camera is controlled by a different controller:
The black, Xbox type, controller is used to control all aspects of the green Double 4K Inspection Camera on the front of the aircraft.
The White, DJI, Flight Controller, is used to control all aspects of the Zenmuse camera on the rear of the vehicle.
In order to switch between the Zenmuse and the Double 4K, the L1 button on the black hand controller is pressed one time. The Ground Control Station (GCS) must be powered and connected to the Omni UAV and black gimbal hand controller.
NOTE: It will take up to 20 seconds to switch between cameras.