Revealing mistakes: When Sheriff Ben Wade pulls Deputy Clyde Sawyer's body out of the water, the dead man is breathing.
Revealing mistakes: When Rocco's boys are out to dump Sawyer's body into the sea, the "dead" Sawyer helps push himself into the water.
Revealing mistakes: Strings on palm trees during hurricane (used to make model palm trees sway back and forth) are visible.
Revealing mistakes: In a scene on the dock as the hurricane is beginning, palm tree far in the distance is not moving whereas Nora's hair and tree branches in the foreground are blowing around. Obviously a painted flat.
Boom mic visible: When Gaye sits down with Nora after being released from her room, the boom microphone is reflected in the picture behind them.
Continuity: When Frank is on top of the boat looking down waiting for the gangsters to come out, a view of him from above shows a shiny plated gun in his left hand. The rest of the scene shows him with a black plated gun in his right hand.
Continuity: Once Frank is aboard the boat with the gangsters, Temple tries to use the hotel phone, but the line is down from the storm. But after Frank has dispatched all of the gangsters, he phones the hotel from the boat and is able to get through. Not nearly enough time has passed for the phone to have been repaired so quickly, especially in such a remote area.
Continuity: The length of Johnny Rocco's tie is constantly changing from one scene to the next, and on and on.
Continuity: During the confrontation between Rocco and Nora (after his shave), the scratch mark from Nora changes sides of Rocco's face.
Factual errors: Describing the summer heat in the Keys, Mr. Temple says that it will cool down in November: "The thermometer will drop to 100 (F, about 38C)", implying that summer temperatures are consistently above 100. This is incorrect. The climate is humid, but the adjacent waters moderate the temperature. Average summer high is 87F (31C). According to the Keys official tourism website, "The hottest it's ever been in Key West is 97º F (36º C), and that was way back in 1880."
Factual errors: Mr. Temple says of the oncoming storm that it is unusual to have one this late in the season, and that they usually happen early in the summer. In fact, the Atlantic hurricane season peaks near the end of summer, around September 10. Hurricanes in early summer (June-July) are much less frequent.
Factual errors: Mr. Temple describes fairly accurately the hurricane that struck the Florida Keys on September 2, 1935. However, his description of the death toll ("800 people washed out to sea") is about double that of the official toll of 408.
Factual errors: Frank says that Rocco's boat anchored just offshore "ought to be away from those reefs with this blow coming up". The coral reefs are much farther offshore.
Factual errors: Many palm trees are correctly shown bending before the winds. However, one rigid, unbent palm topples over (1:06:29). Palm trees survive in hurricane-prone areas precisely because they are flexible enough to bend instead of being toppled.
Factual errors: The hurricane passes by unrealistically quickly.
Plot holes: Near the end the sheriff tells Mr. Temple, Nora and Gaye that the state police have picked up Ziggy and his henchmen as they were about to cross the border into Georgia. It's about 1000 miles from the Keys to the Florida-Georgia border. As Ziggy and his men drove away not long before Rocco and his men left on the boat, and Frank had shot Rocco and his men only about 12 miles off shore, it would not have been possible for Ziggy and his men to reach the border of Georgia by car in so short a time.
Continuity: At the beginning of the film, as the hurricane approaches, all doors and windows are Shuttered. Interior lighting is thus kerosene lamps. Later, the shutters are no where to be seen, and lots of sunlight stream into and light rooms.