They'd must have taken over the hills on foot.
2 seconds sound clip from Radar Men from the Moon - Camouflaged Destruction (S1E7).
You can hear this line at 00:02:27.277 in the Blu-ray version of the movie.
Quote context
[...]
- When Cody gets here, give yourself up. Try not to get too close to him.
- Don't argue, do what I tell ya.
- Don't move. Drop your gun. Where's Graber?
- I got the flying suit under control just before I crashed, but I'd lost my gun.
- When I tried to look for Graber and his pal they had disappeared.
- They'd must have taken over the hills on foot.
- About back where we started.
- Except that we do know that Graber's been hanging out at Al's Cafe.
- They'll probably never show up there again.
- But I might find somebody around there who knows them.
- Anyway, I'm going to give it a try.
[...]