5. Wayne Manor's Security
Remember back in the days of Batman Returns, when Tim Burton foolishly suggested that Bruce Wayne might allow a massive Bat signal to shine into his parlour room - i.e. the place where he hosted guests - and Alfred casually allowed an investigative journalist into the Batcave? How we laughed at the idea that Wayne would be so careless with the security issues surrounding his secret identity, safe in the knowledge that Nolan's realistic Bat-trilogy wouldn't include such foolishness... Except when Bruce Wayne - or presumably Alfred working on his behalf- allowed a casual staff of workers access to the mansion without rigorously checking them when they got there, in case a master thief had concealed herself within the group in order to rob the billionaire absent host of the party or something. You'd think Bruce Wayne had nothing to hide.