This contains spoilers for the ending of The Mist. If you have already seen the movie or don’t mind being spoiled read on, if you do, then don’t. That clear enough?
Well Stephen King and Frank Darabont promised a shocker ending for The Mist and arguably they delivered. Where Stephen King’s novella The Mist ended on an ambiguous note with a vague promise of hope ala Cell, The Mist’s cinematic ending is somewhat promising and yet ominous for humanity, but utterly devastating for David Drayton. Overriding that, the sight of the marching troops is not really in contrast with Drayton’s devastating realization that he not only murdered his son and his friends for nothing, but that in the end the human impulse is no better at the individual level than it is at the government level.
I suspect that Frank Darabont got his idea for the ending of The Mist from the ending of Lord of the Flies, as the navy warships arrive to rescue the boys, who are themselves a microcosm of England and the world. So too the supermarket is in the end meant to be a microcosm of America. The army appears to have won against the creatures of The Mist but at a high price and the decisions they make are not likely to be any better than the decisions David Drayton or the rest of the people in the supermarket made. In the end we’re all human, all flawed and we don’t know what we’re doing.
An ending that completely devalues the journey the characters have gone through is also a bad ending because it jettisons any real reason to care about what went before. (As Stephen King should have learned when he ended the Dark Tower so miserably.) As the ending now tells us, all Drayton really had to do was keep quiet, keep his head down and he and his son would have gotten rescued. Is that really a message Darabont wants to send, especially for a political movie?
I would say that having Drayton howl a second time was a mistake. It’s redundant after the car howling and it would have been far more devastatingly effective and closer to real life, for him to stumble along joining and merging with the soldiers and refugees, shocked and stunned and walking toward a new life he doesn’t know.