I too do not think he was hallucinating because I definitely heard another voice on the 911 call. I think there is a strong possibility he was or had been using again, but am not taking that into account as far as the 911 call goes.
I will take it into account as to what could have possibly happened. I feel there is a strong probability he could have been headed to the area to score some drugs, ran out of gas, came upon some "bad dudes" who chased him and did him harm. Just my opinion. No facts except the 911 call which clearly says Brandon was there with another individual, scared, in trouble and needed help. My BIGGEST question here is why he did not tell his brother what was going on AFTER he called 911. Just does not make sense to me. MOO
I also clearly hear another person say "yeah" and then Brandon says "no I need a cop."
Regarding your question now, here is the info from the Missing Brandon Lawson sight about the call to his brother/Audrey
When Kyle arrived, at 1:10 am, August 9, 2013, there was no sign of Brandon. A Sheriff's Deputy arrived at the truck at the same time as Kyle and Audrey. There was no visible damage to Brandon's truck and his keys and his cell phone were gone. It is understood that the Deputy, nor Kyle, were aware that Brandon phoned 9-1-1 asking for "a cop" as well as stating, "please hurry!" While talking with the deputy, Kyle received a call from Brandon, in which Brandon's cell was going in and out and he was hard to understand. What Kyle understood was "I'm in the field." Kyle, felt maybe Brandon was hiding in the field due to an outstanding warrant from 2 years ago (that Brandon himself just learned and was going to address it the following week) so Kyle made no mention to the deputy of Brandon being the phone call he was listening to. Had Kyle known Brandon phoned 9-1-1 he would never have assumed his brother was "hiding."
At 1:18 Audrey texted Brandon saying "A cop is at your truck" it is assumed she did such as she wanted to warn him due to his warrant. At this time they were not aware that he himself phoned 911 asking for a cop and to please hurry. In statements given to police, as explained by the family, they did admit Brandon's earlier call to them in which he told his brother, and Audrey, that "he was ten minutes up the road, and was bleeding." This was also not reported to Deputy Neal at the scene. It is also understood that Deputy Neal did not report to Kyle that Brandon phoned 911. (It's still unclear if Deputy Neal even know if Brandon called 911)
http://www.missingbrandonlawson.com/2014/02/home.html
It doesn't appear there was a whole lot of communication between Brandon and his brother/Audrey as Brandon phone was cutting in a out.
To answer your question, I simply don't think Brandon had the chance to relay all the details to his brother and Audrey. I believe Brandon's brother when he heard that Brandon was "in a field" and with the cops showing up he assumed Brandon was laying low until the cops left. That all makes sense to me and so does Audrey texting Brandon warning him the cops were at his truck. They had no idea Brandon had called 911 and said he "needed a cop." I don't even think the cop at the truck was aware of Brandon's call for help. The deputy was responding to a completely different call about a truck being in the road.
I have way too many questions about this case.