Well its over and naturally I knew exactly what to expect and was still pretty meh on my answers.
Things I need to be 100% confident in answering for the future:
Dot product (I know what it is but couldn't come up with an example of when to use it in games)
Cross product (ditto)
Quaternions (only sort of know what they are)
I guess I did okay on everything else, although I fucked up the C++ question he asked, I totally got confused when he said sizeof, thinking he meant something about Big O type shit instead of whether the sizeof operator in C++ is compile time or run time.
He called me out on listing 68000 ASM on my resume, but said he appreciated my honesty in answering about how much I knew on it.
I think part of my problem was nerves, and the other part was preparation, sigh.