Encountered several map errors on the urban periphery map set. In particular, I got an assembly with the firebird drop ship sitting atop a small parking structure with the large 4? level parking structure adjacent. The firebird itself has an issue in the back of the passenger space where soldiers have to walk a convoluted path to exit. Additionally, after sweeping the area I got to the top of the garage and found that I couldn't step out of any of the stairwells onto the upper deck. In one case, the soldier that tried couldn't leave the tile he was on and descend the stairs either. 3 aliens were on the top level and at least 2 appeared to not move at all (the first I killed before I could observe). Since I couldn't step onto the deck, I only found them using IR goggles from the level below. By accident, I discovered that I could then shoot through the walls around the top level stair wells. The targeting line was green right through the wall, but the hit change showed 0%. I let loose with a full auto from the assault rifle and it looked like about half the bullets ignored the wall at hit the aliens.