Grissom finds some cigarette butts in a flower pot in the garden. In the close-up, it turns out they can't have been smoked because there are no stains on the filters (otherwise these get brown when smoking from the tar they absorb.)
When they show a close-up of the dead cheerleader at the crime scene you can see her eyelids move and you can see her breathing
During interrogation, Max's mother says Max had an accident and cannot swim. After she states this, the shot of Max is played in reverse. Carefully watch his blinking.
When Nick and Warrick are handling the filters after draining the pool of water, they are doing so without gloves, which is a violation of protocol.