After Richard Strickland's children leave to get on the school bus, Strickland's wife Elaine states she wants to have sex upstairs, but the establishing shot of their house a few seconds earlier does not have a second story.
When Elisa and Giles are arguing about the Amphibian Man in Giles' apartment, Giles folds the Murphy bed up and away against the wall. But as he goes to leave, in the background the bed is visible in the open position on the floor.
When Strickland is shooting at the van with his revolver, bullet shell casings are heard hitting and ringing on the cement floor like an automatic pistol.
During the scene where Elisa floods the bathroom and is shown in full view of how much water is in there, Giles opens the door to see what's happening after receiving a complaint from the lower level of leakage. What he gets is a small stream coming out toward his feet rather than a wall of water that would have come crashing toward at least his upper body from the released pressure.
When Elisa lowers herself into the bath the first time, the water spills over the edge. In the next shot she is still lowering herself, yet the water level is now below the edge of the tub.
The scene with Elisa (Sally Hawkins) flooding up her bathroom has the following problems:
1. Unless she also stopped up her toilet, the level of water in her bathroom would never have risen past that point. 2. Even if her bathroom is only 15X15X15 (conservative estimate), the amount of water would weigh approximately 200,000 lbs (1ft3 water = 7.5 gallons, 8.3 lbs per gallon). 3. Her apartment is shown as being above a theater, with a 1 foot crawlspace with wooden beams. The combined lack of obvious steel supports would have ensured that her entire bathroom would have been dropped into the theater.
1. Unless she also stopped up her toilet, the level of water in her bathroom would never have risen past that point. 2. Even if her bathroom is only 15X15X15 (conservative estimate), the amount of water would weigh approximately 200,000 lbs (1ft3 water = 7.5 gallons, 8.3 lbs per gallon). 3. Her apartment is shown as being above a theater, with a 1 foot crawlspace with wooden beams. The combined lack of obvious steel supports would have ensured that her entire bathroom would have been dropped into the theater.
In one scene they walk past a store selling TV sets. There are about 12 TV's in the window, each one showing a different show, but there were only 3 networks in 1962 and no VCR's.
When Richard Strickland shoots at back of the van he fires eight times from a six-shot revolver.
A 5-star general would not exist in 1962. The last 5-star general was Omar Bradley in 1950 and would have been long since retired. The U.S. military historically has only used this rank during times of war in order to achieve parity with or even outrank allied commanders from other nations under their control in combat.
The general's ribbon bar is upside down. The Silver Star and Distinguished Service Medal were his highest honors, and should be on the top row, not the bottom. His WW2 Victory Medal is much lower in precedence and should be on a lower row, not the top.
Early in the movie, Strickland states he brought the creature back from the Amazon, where the natives worshiped it like a god. Later, as Elisa and Giles are attempting to take the creature from the lab, Hoffstetler, while helping them, says they need to add salt to his water along with the water conditioning chemicals he gives them in a box. The Amazon is a freshwater river, and if the creature was from from there, it would not be used to nor need a saltwater environment. However, that doesn't mean the water has 0 salinity. Amazon river salinity fluctuates over time and space and depending on where the creature is from, 3% (or 30psu) could be the appropriate salinity. Having said that, 30psu is nearly as high as regular marine water.
A WWII era sign is shown, "Loose lips sink ships". It would make sense for a government institution to still be using surplus posters from the war, as they are still trying to discourage the sharing of secret information.
When Zelda is on the loading dock and dials the phone, she only dials five digits. This was possible and functional in the early 1960s; seven digits were not required in some areas.
The water "reflection" on the wall of the lab during the Chica Chica Boom Chic scene suddenly jump cuts revealing it to be a looped projection onto the wall, and not natural light.
Strickland gets into his car while it is pouring rain outside, yet he never seems to get wet as he walks outside into the rain and proceeds to enter his car.
At around 17:50, security is leaving the men's room and you can hear a door latch when the door opens and closes. The door has a handle, not a knob. Therefore you would only hear a thump as the door hit the door jamb closing.
Elisa is moving (and shaking) the surveillance camera upwards but only after Bob sees the image moving up on the monitor.
The creature should not "make bubbles" when it is seen meeting Elisa in the basin the first time.
At around 17:50, security is leaving the men's room and you can hear a door latch. when the door opens and closes. The door has a handle, not a knob. Therefore you would only hear a thump as the door hit the door jamb closing.
A close-up of Strickland struggling with his pain medications reveals childproof ridges on the pill bottle. Childproofing did not begin to appear until 1967 and was not required in the United States by law until 1970.
There are references in the film to the 1962 Cuban Missile Crisis. General Hoyt talks about the Soviet Union putting missiles in Cuba. Also, when Giles drives his truck up to the underground security gate, the security guard on duty has his radio tuned to John F. Kennedy's speech to the nation, announcing that the Soviet Union is building offensive missile sites in Cuba. However, according to Elisa's calendar, the events of the film take place between September 18 and October 9, 1962. The Cuban Missile Crisis did not begin until October 16, 1962, when Kennedy was shown photos taken by a U-2 spy plane showing the missile sites in Cuba. Kennedy did not make his address to the nation until October 22, 1962.
Surveillance cameras in the early 60s, such as those used on the loading dock were MUCH larger than those used in the film. This was either a much newer camera, or someone's guess of what a surveillance camera looked like in those days.
T-8 fluorescent lamps were not available until 1981.
When Elisa and Zelda are cleaning the men's room and Strickland comes in, you see cleaning products on a shelf. The bottle of Clorox has the present-day logo rather than the one from 1962.
The cleaning team can access the lab at any time, without any supervision despite the creature being their "most sensitive asset" and likely coveted by the Russians.
The creature's collar is very wide and would not require much effort to remove as seen specifically at 34'24".
While a great deal suggests that the film takes place in 1962, Strickland and Hoyt agree that they have known each other for thirteen years - 'since Pusan'. The battle for Pusan occurred in 1950, which would make it 1963 when the action took place.
The white southerner uses excuses to avoid serving a black couple in his pie bar. It is 1963, before laws against racial discrimination. So he could have openly refused to let them sit at the counter, or to serve them at all.
The cleaning ladies are seen moping the floor and walking forward at 34'40", thus ruining their effort: the proper way is to mop while walking back.
Elisa gives the wrong sign for the medium egg, she should have used an extra digit.
When Mrs. Strickland comes in carrying a green dessert, she incorrectly called it a gelatin parfait. Gelatin parfaits have whipped cream. What she actually brought out was a molded gelatin ring.