It does in no way defy the laws of anything, except those of the UNA, it breaks a good few of those
I originally intended to show them driving it incredibly fast* and then reach the point where the tracks ended. It being a cliff or uphill they would simply continue on for a a while before landing in the zombie town.
I just went with this because I thought it was funnier.
*That's about the only non-standard thing about it so far.