Random Acts of Violence - S3-E13
Plot hole: While searching through the dead computer guy's CDs Nick finds a CD supposedly burned that night, containing data gathered at the time of death, but by the time the CD was burned the guy would have already been dead, so who took it out of the computer and filed it away?
Random Acts of Violence - S3-E13
Other mistake: Just after they arrest the Janitor, they are walking out of the building past the employee's. The girl sitting at her chair is not actually typing on her keyboard, her fingers never even press on the keys and her screen-saver is displayed on the screen. (00:37:15)