Goofs

One of the German U-boat commanders taunts Greyhound over the radio. This would never have happened in reality. Each Navy ship had a radio signal direction finder and if a U-Boat broke radio silence, triangulation would reveal its exact position.

It was pointed out that Tom Hanks's rank insignia was incorrect for a captain of a destroyer. This is incorrect, as a Navy captain would be assigned to command a vessel such as a cruiser or larger. A commander or lieutenant commander might very well be assigned as the commanding officer of a destroyer. Naval tradition dictates that he is the captain of his ship and is addressed as such by the crew.

At 1:00:00 destroyer with the call-sign EAGLE, calls Greyhound asking permission to abandon ship. This would never happen, as the destroyer captain has full authority to abandon his ship, including when he feels the ship is too damaged to save. This is a naval tradition that dates back three centuries. He would notify the escort commander that he is going to abandon ship, per naval protocol.

During the time of the Battle of the Atlantic all Canadian Flower Class Corvettes were named after cities, towns, and villages (HMCS ALBERNI, HMCS SACKSVILLE, HMCS CHARLOTTETOWN) to distinguish them from British Flower Class Corvettes which were named after flowers (hence the term "flower class"). Canadian ships were (are) 'HMCS' while British ships were (are) HMS. The Canadian Corvette K136 in this film would have been HMCS SHAWINIGAN for historical accuracy.

Shots of the surfaced German subs shadowing the convoy before nightfall show their conning towers unmanned. In reality, the bridge crew would man the conning tower immediately after surfacing, in any weather, to look out for ships and aircraft. They would only drop down again for the next dive.

African-Americans served as mess attendants and as ammo carriers as early as 1942, and before.

Tom Hanks is shown communicating with other convoy ships via radio phone. Inter-ship communication at this time would have been exclusively through semaphore or signal light.

German U-Boats would never deliberately surface close to escort ships as depicted in the movie. They would historically fire a salvo of torpedoes at a target from at least 3 kilometres away while running at periscope depth then dive to escape any retaliation from the escorts.

When the enemy U-Boat is surfaced and fighting against the corvette and destroyer, the captain reveals the sub is too close for the 5-inch and 40mm cannons to hit it. The Fletcher is equipped with multiple Oerlikon 20mm cannons that could easily cause catastrophic damage to the U-Boat and any of its exposed crew, yet none of them fire despite being shown multiple times beforehand.

Depth charges are shown with the classic plume of water resulting from the explosion. This only happens when the depth charge explodes very near the surface and not at the depth a submarine is likely to be. It looks cool and it is what audiences expect, but is not realistic.

Around the 00:58:18 minute mark, when they bury the dead at sea, a hard cut stitching two separate takes of the same shot together can be seen. Immediately after which the muzzle flash of the gun salute is heard a full second before it is seen.

In one brief glimpse near the end one sees the Canadian corvette, call sign Dickie, which the Trivia section notes is a digital recreation of HMCS Sackville, permanently moored in Halifax. It is shown with a red maple leaf on the funnel, which would not have been a part of her livery in WW2. Canadian warships of that time had no insignia on the funnels. On the contemporary Sackville the maple leaf is green.

The fictional titular warship is shown as one of the American Fletcher class destroyers, the most common destroyer class in history, with 175 built. The iconic silhouette of a Fletcher is well known to any students of World War II naval history. And some of the movie was able to be filmed aboard the museum ship USS Kidd, a Fletcher class vessel still maintained in her World War II configuration.

The events of the movie are set in February 1942. The first Fletcher class vessels however were not commissioned into service until June 1942.

The movie was based on the C. S. Forester novel "The Good Shepherd". In the book, the fictional destroyer USS Keeling is described as being of the less well-known, less iconic, and less numerous (18 commissioned) Mahan class. The Mahans first entered service in 1936, however, so such class membership would have been actually possible. The book was published ten years after World War II's end, rather than 75 years later for the movie, and such ship class details may have been more familiar to a wider section of society back then. For what it is worth, none of the Mahan-class destroyers served in the Atlantic either, spending the entire war in the Pacific.

Tom Hanks's character refers to "friendly fire" after his ship is strafed by another vessel in the convoy. This term was not in general use until 1947, well after the time the film is set in.

In C.S. Forester's book The Good Shepherd, the flotilla leader is identified as a Mahan class destroyer: USS Keeling. In the movie adaptation, set in early 1942, the destroyer is identified as a Fletcher class destroyer. This would not have been possible as the Fletcher class was not first placed into service until late summer 1942 and most all Fletchers were either immediately dispatched for service in the Pacific or were assigned to "high value" convoys (troop transports, invasion forces, etc.).

Tom Hanks's character uses the phrase "Rum and Coca Cola" in the movie's first flashback sequence. The song that popularized the phrase was written by the Calypsonian Lord Invader, but was not well-known in the US until the 1945 cover version by the Andrews Sisters, released in 1945 and after the film's time range.

At about the one hour mark, Greyhound's captain calls the British ship "Eagle" for its status and the captain's voice is ahead of his lips moving by a full 1-2 seconds.

Krause refers to the decoy that fooled the sonarman as a 'Pillenwerfer' -- pill thrower. That term was used by the German navy for the fitting that would eject the decoy. The decoy itself was called a Bold, derived from Kobold.

The Royal Navy called it an SBT -- Submarine Bubble Target.