On an airplane the flag on the left side is painted in the right order while on the right side it's painted the opposite way, just like you would look at a real flag when it's flying in the wind.
You can see it in the Belgian registrations:
Viewed from the left: black - yellow - red
Viewed from the right: red - yellow - black
Thus in this case the correct order should be
Viewed from the left: green - white - orange
Viewed from the right: orange - white - green
Example (look at the flags):
