I agree.
Almost as soon as you take off from Narrogin you can see the CBH elevator just north of Williams very clearly. (The CBH termianls in WA are painted bright white and it is not unusual to be able to see them from over 100Km away.) In addition from 4000' QNH (ground level is around 1000') it is (and was on Sunday) very easy to see the Pingelly, Yealering, Wickepin, and Bullaring, etc, CBH elevators. Also the lakes to the SE are very prominent.
To the east of Collie there are large open cut mines and power stations. The mines have very large mounds of white soil around them and all these are visible from Williams. Also at 4000' QNH you will begin to see the sea to the west as a silver or gold fringe on the horizon.
As you near Collie you can see Wellington Dam and the CBH terminal in Bunbury.
So it is very easy to orientate youself in the Narrogin - Williams area and the pilot would have had a number of visual cues that something was not right early into the flight.