I hope it's OK to post to this topic, even though it's been quiet for so long. I've seen this one referenced in multiple places as a definitive thread on Comanche Gold modding, so it seems to make sense for me to post here what I have found.
BAR5 is indeed a hidden menu, although it's not empty on my installation of Comanche Gold. In fact, it contains some rather useful things, not the least of which is an ability to access some of the video recording-and-playback features of the engine. It might be possible to transfer video dumps from one copy of Comanche Gold to another, thereby either showing other gamers how one has completed a mission, or else helping someone along by letting him takeover after a hard part of a mission that someone else has completed.
This menu also contains some debug options, which make it look as if it was used in testing and design by the developers for object placement, among other things. With this menu I was able to "win" the Free Flight mission of the Training campaign -- something I couldn't do before, since there seemed normally to be no objectives to complete to allow me to win.
I'm rather optimistic that the movie features may prove to be some of the best things that could be found hidden in this game.
