1)
Why does it mention the mountains and hills?
1.
Radak: Just like they were specified above in the punishments "Ko Amar Hashem Elokim le'Harim vela'Geva'os?" (6:3), they are specified in the consolation.
2)
Why does it say "Hayu l'Vaz ul'La'ag li'Sh'eris ha'Goyim"?
1.
Malbim: Mo'av did not take from Yisrael's land, and did not take vengeance against them, just they mocked and disgraced them. They will be punished for this!
