There's no muzzle flash in the Mossie's cockpit, when detailed-smooth shadows are enabled...
I'm firing all guns in both images.
                     Detailed Shadows   ON                                                     Detailed Shadows   OFF
 
 
Coogan
<<It's not just the Mossie.  It's pretty much any plane that normally has a muzzle flash visable inside the cockpit.  Even the B-17's gunners>>