Things Clarissa never explained.
space travel.
pop pop
I'd like to answer this seriously. Sorry, people.
Sam's dad. The episode we finally met him was one of the worst of the series and was completely underwhelming. Every other character, from Clarissa's parents to Ferguson and Sam's mom, was fleshed-out pretty well and had an episode or two that dealt with them and their issues. Finally introducing Sam's dad (Five seasons in, no less) should've been a major moment. But it wasn't. He was used as a cheap plot device to further the journalism arc they were going for in the last season. We never learned who he was, what made him tick, his relationship with Sam or anything. One of the biggest mistakes the show ever made, if not the biggest.
The Office died in Season 4. Lieberstien's a hack. Tate sucks. All facts