After seeing these movies a gazillion times, cant see how Ripley drove the APC to the nest to rescue the Marines after the first alien encounter/fight. Gorman parked the APC on the ground/first level and the Marines walked DOWN several flights of stairs to Sub level 3 to get to the hive, It was a long ride by Ripley in the APC into the nest and maybe there was a back way not mentioned, but how does she drive DOWN at least 3 levels to the Marines?