The Batman: 15 Details You Missed The First Time
14. The Seawall's Construction Was Halted
The Batman's big climax involves The Riddler (Paul Dano) strategically parking seven vans next to Gotham's seawall with bombs inside, which he then detonates, causing the city to become flooded.
This is actually subtly set up in the opening moments of the movie, when we see doomed Mayor Don Mitchell Jr. (Rupert Penry-Jones) watching a debate between himself and Bella Reál (Jayme Lawson).
During the debate, Mitchell criticises Reál for wanting to dismantle the Gotham Renewal Program, which he claims is being put to use on "vital projects" such as Gotham's seawall.
However, when Batman (Pattinson) and Jim Gordon (Jeffrey Wright) are investigating Mitchell's murder a few scenes later, a newspaper cutting on the wall bears the headline "Seawall Construction Halted?"
The seawall's construction was presumably halted because, as we find out later, the Gotham Renewal Program became a sham in light of Thomas and Martha Wayne's deaths, where it fell into the hands of the Carmine Falcone (John Turturro) crime syndicate.
As much as a seawall is a vital piece of public infrastructure, it makes sense that construction would be suddenly halted if the fund was being bled dry by Gotham's criminals and corrupt politicians.
This in turn likely gave the Riddler an easier time destroying the walls with his limited resources - they either weren't fully completed or were made from inferior materials.