After Angus is stabbed, the fireman looks at the knife, which is bloody. In the next scene, the knife blade is bloodless.
The flashbacks occur during the 1970s but at 8:14:36, you can see a late model SUV drive past Angus and Vicky while they are sitting in the "beater".
There is nothing on the truck Angus runs into that would have caused the "beater" to flip the way it did.