A couple things on this very fun subject:
30 years ago as a newly minted helicopter pilot, I flew a wrong course and ended up at a towered field thinking I was going to be landing at a non-tower field. About a mile from the tower, I crossed a large hill / small mountain, and saw the control tower. Oops. Since I didn't know where I was, I didn't know which frequency to use. Obviously with further experience I would have known to just give 121.5 a call, but being that I was well below the traffic pattern and there were lovely areas of grass all around the ramp area I elected to just land on the grass and shut down and figure everything out on the ground. Tower was a bit miffed and suggested I have a talk with my instructor, but still to this day I think that landing on the grass was probably a better idea than continuing around in the air while waiting for a light gun signal. Of course, knowing where I was would have been even better!
On the subject of light guns, in the past (at least in the US) light guns had a very wide beam which was very desaturated, i.e. sometimes it could be difficult to tell green from red from white. The "new" ones give a very very saturated green or red light, such that I doubt it's simply a filter in front of a light source. Very nice. The other change, however, is that the beam seems much more narrow, to the point that when tower is trying to hit us with the light gun, it appears to flicker when I know they are actually trying to give us a steady indication. When I practice this, I'm typically 1/2 mile from the tower... perhaps at further distance the beam spread will be larger and less likely to flicker, but I'm curious whether other people have commented on this? It seems like a steady beam could easily be confused with a flashing indication, i.e. tower means to give a steady green, but the pilot sees a flickering green and doesn't think that he's actually cleared to land. Comments?