When Willy is tracking Casey, he is driving a 1967 Lincoln. After Casey meets her contact, and Willy has the accident, he is in a 1963 Lincoln. In the next shot, it changes back to a 1967 Lincoln.
The radio direction finding (RDF) system Willy is using provides a heading to the transmitter. However, with a single receiver, the heading would be indeterminate; at least two RDF receivers, at different locations, are needed to obtain the heading.
The license plate 899 IVC on the green vehicle that Casey is driving, is the same plate used an earlier show this season called Invasion.
When Barney starts up the Lincoln Continental just before the accident, the starter sound is that of a Chrysler vehicle.
After Barney has been shot and is crouching while quickly moving through the estate, there are scenes from his perspective looking towards the house. In these scenes, the shadow of the cameraman and his camera are clearly visible on the bushes and shrubbery in the foreground.