All the episodes have either recurring characters or characters who become recurring later on in the series.
They all have the letter e in the most common letter in the whole alphabet I've cracked the case. :lol:
I wasn't going to guess because I went last time, but since it's been so long... are they bands/groups/singers who have been featured on the show, or have had their music played in an episode?
They are all bands who've had their music on the show but there's somthing more that connects them. If you need to look it up it's sort of hard but not impossible.
Is it that their songs play at the start of the series finales. Or maybe they all play during an important moment outside Mac Taylor's CSI life.