i've seen it happen on other maps like crashed ufo for example, so it probably has nothing to do with the map itself.
On the map are 3 visible aliens, but the counter on the top right says 4. When i click it 4 times i'm back at the 1st alien, the 5th is the 2nd and so on, so i guess there aren't 2 aliens in the same space.
happened in r26082 and r26164
edit: ok, after that green fellow killed his comrade he alone counted as 3... after killing him (last alien) the counter went down to 2 and the map was finished.
