I'm not referring to Ratchet and Bumblebee shooting at it at the end. I've seen it 5 times now and I still have no idea why the corner of the building which was holding the pillar exploded. I didn't see any missilles, I didn't see Optimus shoot at it. Does anyone know?? I only see the building explode and Sentinel tries to reach for it before it falls, that's it.