Essentially, you can use the laser targeting system to destroy the rocks on the riverbed walls. Doing so created a number of interesting and fun events, like a few seconds of intense lag as the hitboxes are updated, along with some possible graphical glitches if looking at the affected rock.
Afterwards, the rock hitboxes are gone, but the rocks are visually still there. This allows for one to build roads and such inside the rocks.
Additionally, as I did not see anyone else cover these bugs, I did notice 2 more things. The first is that the laser targeting building should not be able to be placed in multiple locations at once. The game correctly recognizes that only one laser can exist, but does not sync the queues of the buildings, so you can delete a building with a queue and the laser will still keep destroying those rocks, although no building exist that actually says what the queue is anymore. Secondly, if one builds multiple spaceship repair buildings, if there are any extra rockets in the air when a section is finished the rockets will freeze midair.