Before each game they print out entire lists of things like "the last time x happened" and have the date etc.
So you might have someone get a safety on the first down in the third quarter for the first time since 1902 etc - but the list is so huge that it does take a broadcaster to know how to effectively reference it.
some of the random stuff like "BYU is 6-2 when it's a full moon and there is a sale on broccoli" is probably on him though.