The"Snowden" movie and how did he evade our security services?

I saw the trailer for the new "Snowden" movie and I have one question that has never been asked.  How did Snowden successfully evade US intel/law enforcement agencies and make it first to China and then onto Russia?

Its freaking inexplicable!

The dude was a computer geek not a trained operative!  Going from the city and hiding in the woods is one thing (and even that's iffy unless you're willing to live hard) but to make it out of the country?

Snowden didn't have that skill set.  He had to have help.

Did I miss a joint Chinese/Russian mission to extract a defector/agent/useful idiot/patriot(some will argue that what he did was extremely patriotic) from US soil?