What films take existing technology and repurpose it while maintaining technical correctness?

1. War Games
   1. War dialling
   2. The old payphone voltage dropping trick on an old payphone
   3. Talking with old beards about system weaknesses
2. Blown Away
   1. Bomb blast physics
3. Enemy of the State
   1. Surveillance by RF cams = good
   2. Explosion destroys building = bad, explosions throw stuff; better to build an inferno that melts everything.

That's a really short list. Any other candidates?