Continuity mistake: When the incomplete second EAM is shown in the movie for the first time, its subject line states "nuclear missile launc..." However, when this same message is finally received at the end of the movie the subject line states: "terminate launch all missiles". If the first one had been consistent with the second this would have made quite a difference. (00:55:45 - 01:45:25)
Factual error: Several times during the movie, we can see the radio operator with the screen contents "printed" on his face. As everyone knows, that just doesn't happen in real life. (00:25:00)
Continuity mistake: As the Alabama dives for the first time you will notice that the periscope and antennae masts protruding from her conning tower keep switching from up to down, indicating that the film crew used footage from two different sub dives to achieve that sequence. (00:18:50)
Continuity mistake: When the fat sailor gets on the bus, Dougherty is adjusting his hat with his left hand. In the very next shot he has his right hand on his hat. (00:11:45)
Continuity mistake: When Denzel Washington meets Gene Hackman for the first time, Hackman is holding a cigar in front of his mouth. In the next shot, his arm is suddenly down on the table, and he lifts the cigar to his mouth again. (00:06:30)
Answer: In a war situation, the Captain is absolutely NOT allowed to try and contact anyone, lest it gives their position away, which is why he was unable to question or confirm the order.
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