Even though I enjoyed The Dark Knight when I saw it a few weeks ago, I remain haunted by a failure of the filmmakers to follow-though on an obvious and potentially significant plot twist.
Late in the film, two ferries--one filled with convicts and one filled with "good" people--are stopped while crossing a body of water. The Joker has given the passengers and crew of each ferry a detonation device that will destroy the other ferry if triggered. If neither device is triggered by midnight, both ferries will be destroyed.
There is, of course, a fair bit of drama as people on each ferry wrestle with questions of life and death. One of the convicts throws their detonation device out the window. The "good" people still have theirs, but midnight comes and goes and neither ferry is destroyed, thanks, of course, to Batman.
Throughout the movie, The Joker has played anarchist, providing misleading information--for example, telling Batman his lover was at one address when, in fact, she was at another. Because of this deception, Batman rescues Dent and his lover dies.
One of the themes of the movie is how even the best people can turn bad, and what happens when they do.
So here's what the filmmakers missed:
After the convict throws their detonation device out of the window:
We should see the second hand on the clock aboard the "good" citizen's ferry ticking down the last 60 seconds until midnight.
We should see a "good" citizen finally make a decision and a close-up of his hand as he presses the trigger.
We should see an exterior shot of a ferry exploding. The camera should stay on the ferry wreckage long enough for the viewer to react emotionally.
Then we should see an interior shot of the convicts in their ferry.
The viewer then realizes the The Joker has lied again. The people aboard each ferry had the power to destroy themselves, not each other.
It would have been a much more powerful if the "good" people had destroyed themselves.
But the filmmakers missed that opportunity, or were afraid to follow through on it.