I'm actually not so sure about all that "nothing" we're in, but this was a very nice film.
I wish something could've been said about the Kuiper Belt and the Oort Cloud -- parts of our solar system by some definition.
It would've been cool if they could have said something like that.
From wikipedia the Oort cloud lies at ~5,000-100,000 AU.
So...from memory they made the diameter of Neptune (30AU) at abou 5.6km...so they would need to drive their car at in a circle of diameter between 930-18,600 km.
Possible if their car had amphibious capabilities perhaps .
Space is big.