Towards the end, when the bombers blow up the stadium, you'll notice one of the pilots mention that he is arming 'harpoon missile' or it could be on the HUD, I'm not sure. A harpoon is a missile used exclusively for anti-ship purposes - it would never be used to try hitting a stadium as it isn't even designed to be fired over land.
These are coastal based F-18s right? Designed to defend the coast. Against SHIPS as well as other aircraft. i doubt they would have had time to load them with the appropriate missiles/bombs if they planned on blowing up the Garden in 6 minutes time (see scene in stadium in broadcast room)
The helicopters were firing Sidewinders, which are air-to-air missiles. The F/A-18s were firing Harpoon missiles, which wouldn't work even if that was all they had, and the pilot said he was "arming LGB" (Laser Guided Bomb).