On the night of the 2006 election, Norris watches coverage on CNN. CNN's on-screen graphics match their 2011 scheme, which wasn't implemented until 2008. He's also watching an HD broadcast of CNN; CNN HD did not debut until September 2007.
The agents several times speak of "inflections points", but what they mean is called "bifurcation point", i.e. a point on the graph of a process where a branching into two (or more) different trajectories may occur.
On the Marriage License issued 10/7/2009, Elise's DOB is listed as 11/11/77, making her 31 at the time that this was issued as her birthday for 2009 has not yet arrived. Item 15 (Age) on the license, however, lists her age as 32.
When David is on the bus with Elise she drops his blackberry in the cup of coffee. He receives a call from Charlie on his flip phone. After the scene cuts to Charlie talking on the phone and back to David, David is talking on his Blackberry instead of the flip phone. This is one continuous conversation that should have been done on one phone.
When David and Harry are talking on the boat (a Circle Line tour boat), the visible shoreline on both sides changes between up and down river repeatedly, inconsistent with and much more quickly than the implied motion of the boat.
When Elise is watching David's 2nd interview with John Stewart on TV, David is wearing the same dark blue suit and striped tie that he wore in his first interview at the beginning of the film. Moments after the 2nd interview, when David is led into the empty warehouse by a member of the bureau, his tie is solid dark purple.
David could have been able to find Elise by using any good PI. He could have given a good description of what she looked like, and as many results as his internet search produced, he could have looked in the White Pages, looking solely in the Greater New York area.