At the end Carter recites, "Neither rain or snow or gloom of night..." which is generally believed to be the official motto of the US Postal Service. Actually, an architect of the 1914 New York City Post Office was the son of a scholar of ancient Greek literature. He decided on his own to have an English translation of a classic quote carved over the main entrance. "Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds." is a line from 'The Persian Wars' written by Herodotus about 500BC.
There is a reference that they took Schultz into the army 5 years ago.
Sergeant Schultz accidentally discovers Gestapo involvement in the black market, resulting in Hogan and crew saving him from a transfer to the Russian Front. A black market is a clandestine market or series of transactions that has some aspect of illegality or is characterized by some form of noncompliant behavior with an institutional set of rules.