Ducky mentions not having been at as high an altitude since hanging decorations for his nephew's birthday party. We later find out that Ducky only has one sibling, a half-brother who died young, so wouldn't have had children.
During Corporal Ramsey's interrogation it is revealed that a Marine had a duplicate key for their workshop made. He then produces an original Baldwin key and asks to see Ramsey's key ring. Sure enough, the same original Baldwin key. Baldwin locks are high end residential hardware, and are never used by US military. And copies don't have factory serial numbers on them.
During Gibbs' "interrogation" of Lt. Bud Roberts from JAG (1995), a crew member can be seen in the mirror (when there are only three people in the room: Gibbs, Todd, and Roberts).
As Special Agents Gibbs and Todd interview JAG Lt. Bud Roberts in the interrogation room the camera pans from Robert's to Gibbs'. The reflection of a white male crew member wearing a greenish tee-shirt over a mid-sleeve light colored shirt can be seen in the mirror.