I heard what the OP heard. Guiliani puts up his hand as if to say, "Oops, I wasn't supposed to say that, strike it from the record." He does not say, "Excuse me, I meant former Senator Biden."  That would have beem a harmless correction, if that really was the mistake. Maria also heard Graham=former senator.  She pauses, looks for confirmation or direction from someone off camera, and discretely does not follow up. Yes, I believe these interviews are scripted, just as those on CNN and MSNBC.  Rudy slipped clearly off script. They both let it pass. Can we expect a Graham resignation soon?  It appears so from this accidental reveal. Or is Rudy sly enough to have done this accidently on purpose?