The external antenna is shown breaking away from the ambulance. For some reason, Roy needs this for the bio-phone, which has its own antenna to communicate. The bio-phone has worked in the most remote areas around Los Angeles. For some reason here, the internal antenna fails.
Squad 51 pulls all the way into the station and turns off its headlights while Engine 51 is still pulling in. When the view switches, the Engine has pulled all the way in while the Squad is still backing in with its headlights on.