Even if you're on the Five-0 Task Force, the police will not let you just walk away from the scene of a fatal accident.
Despite what dog worship propaganda wants people to believe, dogs do not understand the concept of death and do not have human emotions. Therefore, a dog would not have PTSD from seeing its owner being killed by a bomb as it does not understand death. It also would not be triggered by flowers yet be perfectly fine around bomb blasts.
During the accident the airbags are not activated knowing that the car that Danno's drives is a recent model.