I do think they have a long list of questions to pick from in each category, because while I have seem some questions repeated, it has never been all 20 of them.
For example, TV Theme Song trivia. Most of the times I have played it, the questions were a good mix of songs from all eras and genres. The last time I played, the Fun Squad member was a 20-something American hipster-type (not that there's anything wrong with that), and most of the theme songs were from cartoons of the late 90's - early 2000's. Hardly anyone over the age of got more than a handful correct.