Going through the Maller war again, Kalani as a spy for the second tower makes sense. The plant at the WA tower defected and stopped contacting the Mallers. Why didn't the Mallers attack the WA tower while the trained soldiers were away? They left Paul and Pegs on guard with one gun. Pegs might as well as made a sign that said "take us over now" It must have take a couple of hours to find a route to the stadium. Come on, Bill enough time to steal the food and ammo.
Everyone gets back and they accidentally stop the zombie attack. Kalani had plenty of time to contact the Mallers to see if Hannah were still alive. Durai or Scratch threatens to kill Hannah again and Kalani spills the beans on the party and the ammo situation. The WA tower spy (who i think is Steven) sees Durai takes a shot at him, and the war starts.