Mad Max Fury Road. They defeat the tyrant, and get the control of the water valves. Then they open the valves and seemingly keep them open. One problem, how long is the water reservoir gonna last now?
Logan’s Run. The city dwellers are freed from the computer’s iron-fisted rule, and Carrousel. But their city is in ruins, and thinks to the computer providing everything. They don’t know how to live without it. The city dwellers are going to start dying off real fast.
Samurai Commando Mission 1549 (spoilers for an obscure movie follow)
The Japanese self defence force gets sent back in time to defend the future from the japanese self-defense force sent earlier back in time who is trying to derail history for… no reason really. This is apparently destroying time itself by altering history!
They stop them by blowing up a bunch of stuff and leaving tons of modern tech (including a nuclear weapon, helicopters, tanks, tons of automatic weapons, and an entire oil refinery) in feudal Japan. The movie suddenly ends on a freeze-frame with characters smiling, but none of these issues addressed, which I always understood to mean that they failed and time was destroyed, leaving them forever frozen in that moment.
The movie was unexpectedly hilarious overall. The guy that hosts Iron Chef is in that movie, and is the best character.
