Yes, I noticed since I wrote the original, but that might be smoke. It's not obvious how the system would work without some sort of dedicated pathway that remains the same day after day. The word "tube" leaps to mind. :)
I'm not so sure about the right-of-way issue, since we are talking about a permanent structure. The case law that weakened the old "Cuius est solum, eius est usque ad coelum et ad inferos" ("for whoever owns the soil, it is theirs all the way up to Heaven and down to Hell") rule, as far as I've seen, all involved aircraft passing over land. I'd not be surprised if a court considered that case law irrelevant when it comes to permanent structures overhanging someone's land.
>However, while the Court rejected the unlimited reach above and below the earth described in the common law doctrine, it also ruled that, "if the landowner is to have full enjoyment of the land, he must have exclusive control of the immediate reaches of the enveloping atmosphere." Without defining a specific limit, the Court stated that flights over the land could be considered a violation of the Takings Clause if they led to "a direct and immediate interference with the enjoyment and use of the land."
Would a hyperloop cause direct and immediate interference with the enjoyment and use of the land? It might if it failed!