Rookie Zoe Martinelli's murder case is first mentioned in Season 1 Episode 1 Fresh Paint when Detective Luke Callaghan formally introduces himself to Andy McNally.
When the woman whose husband was in the fire arrives at the scene and sees the burned building, she gets out of the car saying "Bozhe moy!" three times, which means "My God!" in Russian.
Goof: When the officers are looking at the photos from the shooting, Diaz prints a photo to the "Main Bullpen Color Laser". The printer that is on the desk printing out photos is an inkjet, not a laser.
Goof: When the girl in the red coat is shot and Andy is sprayed with blood spatter, in the lower right quadrant of the frame, you can see the crew member's hand and bottle spraying Andy with red liquid (fake blood).