Toward the end of the episode, Stone and keller board a Coast Guard hovercraft, which began speeding outbound toward the Golden Gate only to be seen moving the opposite direction with Alcatraz in the background. Basically, it started moving north and shortly later was seen moving southbound through the bay, hence in circles.
Mike Stone: I'm a cop, Joe. And I say you're scared.
Reggie Norris: Now there's no reason for both of you to sleep with the fishies.
German episode title: "Lästige Zeugen", meaning "Annoying Witnesses"
Location: Esquivel Fuel Dock