The "Brooklyn Market" Samir goes to get the brown bread is the Italian Market in Philadelphia, likely somewhere along Passyunk Avenue. A sign for the Pennsylvania Lottery can be see on a storefront in the background.
Omar tells Maya that he has not been around, because their college experience will soon be over, and he has been packing. Then we see the reports of 9/11. But 9/11 happened at the beginning of a college semester, not near the end of one.
When Sam is playing chess at the University with the Asian guy, the board is shown from the top; there is one chess cube free between the two kings. In the next scene the kings are shown next to each other. That is not possible because both of them would be in check. Plus, Sam is making checkmate by taking the white king with the black king. That is against the rules of chess.