'Take the jet'

I doubt you are American.
Distances in US are vast, compared to Europe. For example, Manchester (UK) is within a day's driving distance of London,easily, but by choice, I'd take a private jet.
I worked with a huge US engineering company in the Gulf in the late 70's/80's and many locations, one could say were within good driving distance, but almost all Brits & Americans opted for, or were informed to take the company aircraft, advantages being leave and arrive almost exactly when we wanted and met by car. (We were not all senior personnel btw, just that was our company culture. We had 3 private company aircraft available). Other large corps.also owned private jets for expat.personnel use. (Salad days,buddy!)
I recall that line in the movie, and didn't find it in the least remarkable.

IIRC, he said its "in driving distance" and by that he meant in driving distance from the place where the assassination happened, not from where they were when having the conversation at this moment.