The first and last exchange between Idris Elba's character and Paul Walker's character are exactly the same, albeit the lines are switched the second time around.
The characters John Rahway played by Paul Walker, and the Attica brothers played by Chris Brown and Michael Ealy are all named after prisons. Attica is in Upstate New York. And Rahway Prison is in New Jersey.
Before the armored car heist, John puts an automatic rifle together with a scope. He then sights it in. Then between shots of him during the scene, a set of scope cups is alternately on and off the scope. With the scope cups on he wouldn't be able to see through the scope.
When Cozier went to visit his sister in rehab as they are talking a woman that sits on the bench can be seen sitting in the bench in some shots and gone in others.
After the gunfight with the Russians at the hotel, AJ is lying on the floor, dead. When the others start to gather around him, for a couple of seconds, you can see him breathing.