The trouble with blowing a hole in the tube somewhere to re-pressurise is that whatever is inside the hole is hit by a wall of air travelling somewhere around the speed of sound. There are a LOT of problems with hyperloop not limited to someone walking up to the tube and shooting it with a .50 Desert Eagle, earthquakes, and the expansion and contraction of the tube as the sun rises and sets.
It's definitely the most unlikely of Elon Musk's plans.
It's definitely the most unlikely of Elon Musk's plans.