How about something like the suspicious activity call but in more special and strategical places? I remember when I went to New York the MTA ESU entering the subway and patrol there, so something similar here; you have to go to the subway, Times Square or to other important places, and patrol there by foot.
In the subway would be nice because you'd have to enter by the station, where all the people goes, and then by the subway tunnels, so there would have to be careful with the subway crossing. In the tunnels also there would be needed the flashlight.
Another entrance could be that subway emergency exit that where you left the tunnels in the mission of the bank robbery; besides, by that entrance, there is a room with machinery or something so, so it would be a great place for investigate.
In that call, you could encounter from a gun/drug dealer to a fallen person, or it also could be a false alarm.
Another idea is a police drill, where you would have to patrol through the city, going by some waypoints, with many police car more. Something like this, but going a bit faster: