This page was one of my favorite of the story, not because it looks so cool, but because of the idea behind it:

Airport screenings are always so focused on some threats that it seems like other clever/evil ideas might be able to get right by the screening process. Do we really need to keep taking off our shoes or worrying about tiny bottles of liquid? Who looks closely at the air tank and/or air compressor of a disabled passenger?
In this story, no one does.

What if someone smuggled weapons in one of those oxygen tanks? It could even still be a functional air supply if there was just a smaller tank hidden in a big vessel. Who thinks of that?

Or what about the certification required for those air tanks? How hard would it be to fake those forms?