On the episode "One Last Trick", Mike Stone and Dan Robbins were leaving to investigate a clue. Now, I haven't seen this episode in a long time, but when I did, I noticed it right away and still remember it.

As they were leaving the Homicide Unit office, Lt. Stone says to Insp. Robbins, "Come on, Steve". Well, "Steve" is Insp. Steve Keller, who had already left the Dept. Insp. Robbins' first name is Dan.