When leaving the victim's house the second time, Gibbs puts away his notebook twice in succession.
66-3T6 is not an actual type of aluminum. 6061-T6 and 6061-T3 are. The dash T+number denotes the hardness temper of the material. The number proceeding the dash describes the chemical composition of the aluminum, and is always four numbers. (e.g. 2024, 3035, 6061, 7075, etc).
Abby pronounces "espresso" with an "x".