Matt Coleman on the tour bus spotted the right comms panel door open while we waited for the aircraft to taxi in front of us enroute to the runway. Vic Lopez, well-versed in aircraft maintenance, confirmed that the door would not shut itself inflight. Ralph Cruz, on our bus from MDAD Airside Ops, radioed the information to one of the gate control towers to call the FAA Tower about the issue and have the flight return to the concourse to have a Delta ramp worker properly shut the door.