After Lt. Caine and Delko find the tanks of Halon on the roof, Horatio is shown handling one of the tanks with his bare hands. This would have compromised any fingerprints on the tank. And he did this in spite of the fact that he had just been shown with latex gloves.
When Calleigh weighs the recovered round, she makes a comment on the weight of the round. The standard weight she quotes is correct for a .223 projectile, but not for a complete round, with casing and propellant intact.