The murder weapon is referred to as an M11-A1. And was supposedly issued to officers in Vietnam.
The truth is the M11-A1 is a Sig-Sauer 9MM pistol. And it's issued to Naval Aviators. It is a design of the last 15 years or so. It would not have been available during the War in Vietnam.
During the funeral, Detective Eames looks at a portrait of herself. It was said to be taken on St Patrick's Day of 1995, at the time over a decade in the past, right after she got married. She is wearing exactly the same dress uniform as in the picture. As a decorated senior detective on the Major Case Squad, her rank, precinct, commendations, service bars, etc would have been quite different than they were 13 years previous.
US military personnel and veterans never refer to the Colt .45 Model 1911 automatic pistol as the "M11". It is known by several other nomenclatures, such as "Colt .45 Automatic", "45 Auto", "Model 1911" or "M1911", but never the M11, which is an entirely different pistol introduced much later to the US military than the era than of the weapon referred to.