When the Checkmate agent commits suicide, there is a great deal of blue foam all around his mouth as he is dying. Then, after he is dead, there is only a small trickle of blue foam from the corner of his mouth.
After Tess rolls over the hood of a car during the fight early on in the streets, the driver tries to open the door and Tess kicks it closed breaking the glass window on the driver's head. The glass shatters into many large shards of glass, but auto glass is made of tempered safety glass that is designed to crumble into small granular chunks of similar size and shape instead of splintering into random, jagged shards. The granular chunks are less likely to cause injury.
On the chessboard in the opening sequence, Black's pieces are set up incorrectly (the starting squares of the bishop and knight on Black's queenside are reversed).