At about 54:50 There is a lamp lit in the tent with the Adm. & Gen. At 55:40 the lamp is out. No lamp would have been lit in a combat zone anyway.
When just before & during the Adm. getting his shots the clock on the wall never changes. It stays at 9:10 or or so. This is from 1:03:40 to about 1:05:57.
At one point, when ADM Halsey (then still a VADM in the movie) is meeting with his force (air/ground) commanders on-board ship, we hear eight bells to signify the end of a watch. This would put the time at either 8, 12, or 4 (a.m. or p.m.), yet moments later there is a shot of Halsey (Cagney) with a ships clock in the background on the wall of his office/quarters and the time is 10:30, (1030 or 2230 if it is a 24 hour clock) which would be 5 bells.
In the meeting of the top commanders, Rear Admiral Kelly Turner first talks, then is introduced by the narrator, then talks again. In the background is a clock. In the 3 consecutive scenes the clock goes from 20:17 to 20:25, then back to 20:20.
At the beginning of the move its stated that he retired on 22 November 1945. Halsey actually retired in March 1947.
On 22 November 1945, Halsey did not hold the rank of Fleet Admiral. He took the oath of that rank three weeks later, on December 11, 1945. Further, he did not retire on 22 November, he hauled down his flag for the final time on that date from his flagship, the battleship South Dakota. He then served on special duty in the office of the secretary of the navy until his retirement from active service in March of 1947. But, due to his final rank of fleet admiral, he remained on the Navy active duty status until his death.
The timeline is convoluted. Events are compressed by many months, such as the Yamamoto interception (April 43) overlapping the naval battle of Guadalcanal (November 42.)
When Admiral Halsey visits with Marines on Guadalcanal, they wear camouflage covers on their helmets. In fact, those covers were not in use on Guadalcanal, and Marines there wore bare M1 helmets. A few may have worn burlap as a helmet cover, a practice picked up from Marine Raiders. But camouflage covers of the kind used in the movie were not present on Guadalcanal. (Reference: United States Marine Corps Uniforms, Insignia and Personal Items of World War II by Harlan Glenn)
Approximately 15 minutes into the movie, while flying to Guadalcanal, the radio operator hands Adm Halsey (James Cagney) a message. The contents are there was increased radio traffic to the Japanese on Guadalcanal. The radio man states he 'picked it up' though it wasn't addressed to them.
The scene shifts to a call between Admirals Nimitz and King. Nimitz states that Halsey is in the air and does not have coding equipment.
If Halsey did not have coding equipment on board the transport plane, the radio operator would not have been able to 'decode' the message he'd just handed to Halsey? Minimal communication was transmitted "in the clear" (i.e., not encoded). A message indicating unusual radio traffic between specific 'enemy' bases would certainly not have been transmitted in the clear.
The scene shifts to a call between Admirals Nimitz and King. Nimitz states that Halsey is in the air and does not have coding equipment.
If Halsey did not have coding equipment on board the transport plane, the radio operator would not have been able to 'decode' the message he'd just handed to Halsey? Minimal communication was transmitted "in the clear" (i.e., not encoded). A message indicating unusual radio traffic between specific 'enemy' bases would certainly not have been transmitted in the clear.
Near the end of the film the Battle of Cape Esperance is taking place. At the same time as the ambush of Japanese Admiral Yamamoto. In fact, the battle took place on the night of October 11-12, 1942. The death of Yamamoto was April 18, 1943, six months later.
The film uses F6F Hellcat fighter planes, which were not in combat service in 1942. Also, the F6Fs used in the film have wing-tip fuel tanks, which were a post-war innovation, not used in WWII.
When Halsey arrives on Guadalcanal, he gets out of an R4D aircraft (the Navy version of the C-47 or DC-3) with 17271 painted on its tail. Painting of tail numbers was required for Army Air Force aircraft but was rare in the Navy or the Marines. Nevertheless, Naval Bureau Number 17271 was indeed an R4D-5 (former USAAF 43-48513) but was not transferred to the Navy until 1 Sep 1944, two years after the time frame for this film.
During the early scene where the Japanese submarine crew spots Halsey's airplane, when the lookout raises a pair of binoculars to his eyes the pressure marks of a modern metal watchband are visible on his wrist, indicating the actor removed the watch just before the take.
When narrator Robert Montgomery is talking about Admiral Turner's re-supply mission to Guadacanal, about one hour, twenty minutes into the film, there is a shot of the U.S.S. Weaver (DE-741). That ship was not commissioned until 31 December 1943, more than a year after the time in this film.
In opening narration it is Nov 1945. The narration states Halsey was born 62 years ago this date that would be Nov 1883, but he was born in Oct 1882 13 months prior, it also says he is retiring this day but he did not retire from active duty until Mar 1947.
Dennis Weaver's character "Lt. Cmdr. Andy Lowe" is the same rank in 1942 that he is in 1945 after 3 years of war serving on the Admiral's staff and as a fighter pilot. When saluting the departing Admiral Halsey (James Cagney) he has no embellishments (scrambled eggs) on his cap meaning he was never promoted from his 1942 Lt. Cmdr. rank.