It's not just time zones and leap seconds. SI seconds on Earth are slower because of relativity, so there are time standards for space stuff (TCB, TGC) that use faster SI seconds than UTC/Unix time. T2 - T1 = [God doesn't know and the Devil isn't telling.]
There are... 2 sequels
Good luck finding them though!
There's link in the description, it's just that those are a bit costy ($8 just to watch on Vimeo)
Ouch. Yeah, I don't want to know that badly.