Quincy expresses surprise that the "War Dept." never notified Charlie Sr of Charlie Jr's supposed death in Vietnam. The War Dept per se ceased to exist in 1947 and was replaced by the National Military Establishment, now known as the Dept of Defense.
When Quincy goes to Lubbock, Texas, to trace the young man he has identified, he goes to the Medical Examiner's office. In 1977, Lubbock didn't have a Medical Examiner's office - a local pathologist did autopsies under contract.
After Quincy picks up Hal Borden to meet Frank at the Courtland house, the rear license plate on his black Coroner's (AMC Matador) station wagon can be seen and reads [E]22596.
The headline in the newspaper Lt. Monahan shows Quincy reads, "ALAS POOR YORICK, I KNEW HIM WELL", which Quincy also reads out loud. The actual quote from "Hamlet" is, "Alas, poor Yorick! I knew him, Horatio"
Quincy tells the cop that he is the M.E. of the STATE of Los Angeles. He likely meant to say the COUNTY of Los Angeles.
Quincy claims the missing man was a male Caucasian, age 22-23, 198 lb., 6'-3", blood type B, and even draws a diagram showing his face with blond hair and blue eyes. While he could presume his general height and size with the found bone, there was no way he could have known the info he claimed to know based on the technology of that day.