Near La Sal Junction, Utah
The Indian Teleport / Hovekeep Ruins is made up of a series of low stone walls - if you can get to the center while the green lightshow is taking place, you be transported acroos the arena, collecting a variety of weapons and powerups on the way. If you're on the road above, you can take out the barriers and drop into the ruins quicker than navigating the walls, though it does require a degree of accuracy...
The bridges allow quick access from one side of the level to the other. Destroying them means that heavier vehicles will have to take the long route round, while lighter ones may be able to power up the inclines.
Falling Boulders (Marked on Map)
Falling boulders can appear almost anywhere on the level, though more likely round the perimeter. Firing at a hotspot will immediately cause a large boulder to drop into the arena, rolling about damaging any vehicles it hits. You can also unleash several boulders at once, increasing your chances of hitting an enemy. If you get sick of them, you can destroy them with a few hits - be careful, as they break into medium-sized boulders which need to broken into smaller ones before being taken out completely.
Weapons & Powerup Spawn Points
Nowhere really specific to head for, bar the Teleport, though the gas station is quite a good bet for a wrench. Otherwise, check the locations indicated on the map.