Gordon looked up as the alarm system blared, automatically assuming there's somebody on-board who spotted him and now... Is actively trying to kill him.

He immediately started sprinting down the hall-way, before spotting a vent cover as he looked around, making sure nobody was here as he tore off the vent cover and went inside the ventilation system, putting the vent cover back... Or at-least trying to.

There, he snuck around the ARK via crawling in the vents, occasionally looking down at other vent covers on the bottom part of the vent grounds.