Well it seems likely the military scared off the public and press by claiming the dome is radioactive or something. Although I agree, it seems like there should still be more interaction with the outside world than we're seeing.
And as for rioting, I'm not so sure. In a small town where everyone knows each other, I think they'd probably think twice before attacking
each other and stealing everything in sight. There would obviously be panic and fear, but like in the aftermath of any huge crisis (think 9/11), I think they'd probably band together and try to share as many resources as they could.
Especially after only a few weeks. Maybe if this persisted for several months
, they'd start to go stir crazy and kill each other, but I can't see it happening this soon.