Maybe not properly a bug, but, yes, when you up the strafer version of B-25C (both with "solid" and "semisolid" nose), if you press 2, the number associated with the nose gunner position, you will, of course, get a black screen. Indeed, the position didn't exist on the plane, while it's still there in game, although not listed. It'd be better not to include it at all.
If you press 3 in the C model, you go to top turret: this is correctly labeled in this model, but, as I said above, it'd be better to shift this position to key 2 and erase the nose one (of course, I don't know if it's possible... after all the plane model is the same, with just no glass nose and gun position).
Mipoikel, what you said refers to the H model. Here, if you hit 2, you will be in top turret, but it is labeled as "nose gunner", while if you hit 3, you will be in rear turret, labeled as "top turret". Plus, position 4 and 5 are not labeled as left and right waist gunners, just as position 4 and 5.