Greg changes the number of days ''Since last accident in the work place'' from 1659 to zero. 1659 was a little over 4.5 years, which was the day Greg's lab blew up, S3E22.
This episode shows Hodges, with the assistance of other Lab techs, going through different crime solving scenarios in hopes of making a game called Lab Rats. The name of the game comes from an earlier episode where the techs all got together trying to help Grissom solve the Miniature Killer crimes.
This episode is the second in the unofficial "Lab Rats" sub-series, giving the secondary cast more screen time, and the lead actors time to film other episodes and/or time off. This episode probably is a deliberate self-referential spoof based upon various cliches of their own series.
The Pieces for the Lab Rats Board Games is in the Exact Style as in the Real Life CSI The Senses Board Game, of course the Real Life Version The Game Pieces are of the Main Character of the Show At the Time, and the in Universe Lab Rats Version has the Secondary Lab Tech Characters of the time.
The Lab Rats Board Game is the in Universe Version of the Real Life Board Game with slightly shorter and altered rules