The First Floor

1. Pressing the red button will do the job but...
2. ...fuel is precious, and there's a better way to defeat the missile.
3. The tiny truck has a radar dish on it, which is pointing toward the Atomic Chihuahua.
4. The tiny truck is guiding the rocket toward the Chihuahua.
5. Therefore, destroying the truck will render the missile harmless.
6. Move the Atomic Chihuahua to the east end of the park, near the tiny truck, and then PRESS THE BLACK BUTTON.