The red indicator pops out on the left side of the yoke.
That's the dive flaps, not the regular flaps. That red thing you call an indicator is actually the dive flap controller. You pull it towards you to deploy the dive flaps, and push it forward to retract the dive flaps. The regular flaps are controlled by a lever on the right side of the cockpit. In our cockpit the lever moves when you deploy flaps.
If I recall correctly, the real P-38L did not have a flap indicator on the panel. There was a physical indicator out on the wing. I don't see such an indicator on our Aces High P-38 wing, but I might not have found it yet.