Holy cow, that's McArthur isn't it?
I've never seen that flag either, makes a guy wonder what that story is. EDIT:
I googled it, it was called the US naval jack flag, used in WW2.
I've watched a few videos of the various POW's that were held in the US, about how they were shocked when they were fed beef and given soap and showers, also stationary and were encouraged to write home and tell their families they were safe here. Some Germans worked on ranches and met German descendants that owned ranches. Some of them became quite good at cowboy life.
Some of the Japanese POW's expected to be killed and eaten. When they were fed at first some thought it was a trick and refused it.
Most of the videos aren't historically verified and fact filled but I'm sure there are instances of truth.
In Galesburg Illinois, we had a Mayo veterans hospital that also a small camp with German POW's. On Sundays the locals of German heritage would take them baked goods and treats and were allowed to talk through the fences.