The exploded car seems a bit gratuitous, but amusing...
Yup, before computers, FX was really time-consuming and clever.
A girlfriend in the mid-80s worked at an FX place in SoCal; a fascinating place to walk through.
One of the jobs they did was the mushroom clouds for a movie - called The Day After, IIRC.
They made the mushroom cloud events in a chamber maybe 36" tall.