Well, we all know that the aircraft/GV modelers put in little hidden things. The only one I've found is a mean (and ugly) face on the turret of the LVTA4. If you rotate your .50 cal so it faces the same way as the turret, press keypads 0 and 7 (or whatever you use) and fire the .50 cal (for the muzzle flash) while still looking that way.