I didn't realize L.A. had such an extensive underground tunnel system
The scientist lady mentioned that the city had more than 700 MILES of underground drainage tunnels. I was so impressed by that number (700 freakin' miles, you say???) that I had to look it up (trust but verify, as Reagan would say). Well, in the ensuing 60 years since this movie came out, that number has apparently swelled to nearly 1500 miles, according to this website:
http://www.lastormwater.org/siteorg/general/lastrmdrn.htm
Wow, that's a lot of tunnels. Must've provided a lot of jobs for people back during the Great Depression. Also, this movie, with its nuclear radiation theme and desert and Joshua tree images, reminds me of "Repo Man," which, if you'll recall, also had some scenes which took place in the culverts of the L.A. storm drain system.
"Beautiful evening. You can almost see the stars..." — J. Frank Parnell, "Repo Man"