Castillo tells Crockett to give Billy a hug for him. Castillo did not know Sonny or his family before the divorce with Caroline. Castillo did not join the department until after the death of Lieutenant Lou Rodriguez, who was killed in season one, episode four.
While it is true that Castillo joined the unit after the divorce. A leader as good as Castillo would know his people and their history.
During the opening scene, a gunman breaks the window of the limo. The glass is clearly not safety glass, as it breaks in sheets.