The real Red Ball Express operated two separate roads for traffic (one going to the front and one for returning empty) Two-way traffic on a single road, as shown in the film , never occurred.
The majority of Red Ball Express drivers were African American. The US Army was still segregated during World War II. As behind the line support troops, they were available in large numbers to be drafted into the overnight emergency Redball Express. The film doesn't reflect the demographic realities of the unit.
The German soldiers are shown wearing WWI German Army Stahlhelm helmets. These were long out of service by WWII.