My dad works at the CalTrans building in LA. He saw the Alias crew film the Countdown sequence where they were trying to capture Sark and Irina in the Pharmaceutical building. Then the building blew up. Anywho he saw them film again last Friday and Saturday. He said the roads were closed off and that they had been warned their would be an explosion and gun fire going off. Im think they are shooting for either episode 21 "legacy" or episode 22. Too bad i couldnt see it though.