When discussing a medical examiner colleague in Los Angeles, Ducky comments "they're very strange in Los Angeles". NCIS is filmed primary in Los Angeles County
McGee doesn't recognize poison ivy, though he later is said to be an accomplished scout leader.
The license plate that Abby identifies "107 TIK" is the same plate number as the getaway car Jeffrey and Tony used in "Chained".
Abby identifies the wood in the victim as Northern White Ash, commonly used in baseball bats,with maple being the other common wood. She then says "Someone pulled a Barry Bonds on this guy." Barry Bonds was a famous MLB player who conspicuously used maple bats at a time when ash was very common.