6. Minor malfunctions would be catastrophic
When you’re catapulting inside a windowless vacuum at supersonic speeds, even the slightest disruption to the air around it is game over. There would be airplane-style oxygen masks that drop down in the event of a loss of pressure inside the pod, but what about an unexpected jolt from outside the tube (an earthquake, freak explosion, etc.) that cracks the facade? Or what if any of the air compressors that cushion the pod fail? Either of those scenario ends with an out-of-control, train-sized bullet violently bouncing off the walls. That would be bad.
7. But Musk insists it's the safest "fifth mode of transport"
Despite these safety concerns, Musk maintains that the Hyperloop would still be much safer than the four alternatives -- trains, planes, cars, and boats. Beyond the general convenience of efficient, high speed travel, the Hyperloop would be immune to dangerous weather conditions like fog, ice, rain, or snow, helping to relieve major cities of congested traffic jams and accidents.