The mezzanine of a BMT subway station in Brooklyn was restored to its 1944 appearance for filming. The subway train consisted of vintage 1927-28 articulating Triplex units which had already been retired from revenue service at the time of filming.
The film was spoofed in the December 1973 issue of Mad magazine as "The Clods Of '44."
The film is also noted for being the feature film debut of John Candy in a very brief uncredited appearance at the beginning as a high school graduate who interacts with Hermie and Oscy.
Unlike its prequel Summer of '42 (1971), Class of '44 is more of a fictional work. There are several fictional elements in this film. One of them was that this film was supposed to be based on the boys facing army service in the Korean War. But it was changed to World War 2.
The A sticker on Julie's car windshield is a gas rationing tag. It allows her to buy 4 gallons of gasoline per week. Gas rationing started in May of 1942.