Was there room for improvement?
Surprisingly the graphics conversion to Windows 95 and 98 did not support higher resolutions than 600 x 400... surprising because the original - US Navy Fighters although running in DOS, supported resolutions up to 1024 x 768!
Dodgy flight models on landing.
Dodgy flight models in general.
The F-22 which almost refuses to land!
The frame rate hit around built up areas.... no matter how fast a PC you have the frame rate still drops to 6 -7 fps around the airbases.
The sometimes wildly inaccurate weapon and fuel loads. The best example being the F-111 with 3,000 lbs of fuel... that should be around 18,000 lbs! Mind you the main aircraft were pretty accurate in these respects - out of over 100 aircraft eventually modelled in so many parameters you'd be surprised not to find a few bloopers!
None of these flaws were however fatal to gameplay.