Just a little screwup with the code causing that mask bug. I watched some videos of F-86D pilots during a scramble drill and in general, mask goes on whilst on the ground. The mask contains the microphone so makes sense it goes on BUT no doubt some pilots don't like wearing it unless they need to. JackS probably can answer this better but I believe oxygen starts getting delivered automatically when above 10,000ft.
This bug will be fixed when Crazyflak releases the updated F-80 pack