After being served papers, Lt. Horatio Caine (David Caruso) from CSI: Miami (2002) says, "I have a number of memories up here and not all are good. So I apologize." This is an obvious reference to the very public spat and his eventual departure from his first hit show NYPD Blue (1993).
This is part 2 of 2 in the CSI: Miami (2002) / CSI: NY (2004) crossover. Part 1 is Felony Flight (2005) (#4.7) of CSI: Miami.