The featured location representing a bombed-out military facility, used to convince the villain that he was living in a war-ravaged America in the year 2000, was actually the former Olive View Medical Center in Sylmar, California. Built in 1970, it was irreparably damaged by an earthquake on February 9, 1971, approximately a year and a half before this episode was filmed.
When it's revealed that it's supposed to be the year 2000 Barney is one of the few people to correctly understand that that year is last year of the millennium, instead of the more commonly presumed 1999.
Jim's taped message says the amount of plutonium is enough to make a dozen Hiroshima sized bombs. It wasn't commonly known that two different bombs were dropped on Japan in 1945. The one used at Hiroshima used an enriched uranium material, and it was the one dropped on Nagasaki that used plutonium.
There are several isotopes of weapons-grade plutonium. The most commonly used variety, Pu-239 (mentioned by Collins), has a half-life of 24,000 years; others have half-lives as short as fourteen years. Based on 1970s nuclear technology, Collins' 50 kilograms is enough to make seven or eight Hiroshima-sized bombs, but could pose a lethal risk to anyone handling it.
Joanna Cassidy, who plays the fashion model at the beginning, would have two more roles in the series, both as a stewardess. Then in 1985, she starred in her own television series named "Codename: Firefox", in which she played a sort of female Jim Phelps leading a covert team of female counter-intelligence operatives.