Tim Russ who plays band member Felix Hill, is an actual musician.
Tim Russ and Scott Bakula were both part of the Star Trek franchise. Tim Russ was Lieutenant. Commander Tuvok on Star Trek: Voyager (1995) and Scott Bakula was Captain Jonathan Archer on Star Trek: Enterprise (2001).
Incidentally enough, both the Star Trek and NCIS franchises fall under the banner of the same production company, CBS Television Studios.