That bank at the end was pretty lax with their password security. "Just say it out loud. Hope no one hears it." Also, that is a really obvious password to use especially considering how famous the heist must have been afterward.
Why was the bank spelled World Banc? If you didn't want to copy "World Bank" for legal reasons, why not use something other than "World"?
Other point about the horrible choice for Dog Day Afternoon. The reason Pacino's character is so memorable is because he is so nice to the hostages. Kind of changes the dynamic of the movie if he starts killing all the hostages.