Ok when the Cops spy on Lil Cube and see him delivering Chinese food to the Fed Reserve wouldn't they logically assume it was their next target? That coupled with the theft of an empty armored car should have been easy to put 2 and 2 together, It's like it never crossed their mind.
Some major plot holes but still a fun movie.
Disclaimer: Views expressed in this post reflect the opinions of Texags user bonfarr and are not to be accepted as facts or to be taken at face value.