Near the beginning, when Kenneth Woods gets his tie caught in the truck's engine, the tie wraps around the top fan belt pulley. A few shots later, as Woods begs for his partner to cut him free, the tie is no longer around the pulley.
At one point during the "out-of-control truck" scene near the end, Jack Monk's seat belt becomes unbuckled. When the shot switches to Monk then back to Jack, the belt is back on Jack and it seems unlikely that he would have bothered to buckle it given the danger that he and Monk were in.
When Monk is in the diner with his father Jack, he gets upset that his food is touching on the plate. In response, Jack grabs a single extra plate and transfers the carrots onto it. The next time the table is shown, there are TWO extra plates on the table, and the second plate contains the mashed potatoes even though Jack never actually grabbed the second plate and transferred them to it.
When Adrian & his dad are in the 18-wheeler, they can't stop the truck because the brake line broke. 18-wheelers actually use an air brake system, not fluids. As soon as the line opened, the brake system would have depressurized, and the brakes would have engaged.
Tractor-trailers do not have hydraulic brakes - they are equipped with pneumatic braking systems. If the line breaks, the result is that the system depressurizes. By default, the brakes would engage and the wheels would lock up.
The total gas price is inconsistent with the price per gallon and the number of gallons pumped.
Jack Monk was filling his truck's tank with gasoline, not diesel fuel.
Truck runaway ramps go up hill and consist of soft sand or gravel to slow a runaway vehicle down. The close-up of the truck wheels on the runaway ramp showed the truck was on hard ground.
Midland, Texas, is shown with lots of trees and mountains in the background and rolling terrain. Midland is, in fact, flat and featureless and this episode was obviously not filmed there.
It's amusing, but the writers use the peculiar Los Angeles, California manner of speaking in referring to highways as "the 209" and "the 402". Texans would say Highway 209 and Highway 402. They don't use "the" in front of highway numbers.