Final answer:
A red lantern on the rear of a car on a lay-up track indicates that the car is driving in the opposite direction or against the flow of traffic.
Step-by-step explanation:
The presence of a red lantern on the rear of a car on a lay-up track is an indication that the car is driving in the opposite direction or against the flow of traffic. This is commonly seen in racetracks where cars are driving in a clockwise direction. The red lantern serves as a warning for other drivers and helps to maintain safety on the track.