Revealing mistake: When the California Seismological Institute collapses, the old boss is replaced by a much younger stunt. Also, his sleeves swap between rolled up or not and his tie disappears.
Revealing mistake: When Stewart climbs up the rope to save Sam, in the wide angles he is replaced by an obvious stunt: younger and with different haircut.
Revealing mistake: When the car chase comes to an end, check the curb where the cars drive over: a small ramp has been placed to allow for the stunts.
Revealing mistake: When Adams is inside the trench and dirt begins to pour, he is replaced by an obvious stuntman with a totally different hairstyle.
Revealing mistake: When Denise picks up Corry, he has a silver patch underneath his shirt. Seemingly some sort of protection.
Revealing mistake: When the highway collapses, the miniature prop is missing the delineators and lamp posts.
Revealing mistake: Near the beginning, after a couple of small earthquakes, Fred comes flying out of the dam elevator shaft with a whole heap of water, dead from drowning. But you can see him lift his head out of the water seconds before his friend turns him over and finds him definitely dead.
Answer: That has been a question of debate for years. Some say he died, others say he lived. The only real answer I can give is, there were talks of making a sequel. In it, Lou and Maria were living in San Francisco, while Miles and his partner were headlining his motorcycle act in Las Vegas, when another, stronger earthquake hits.