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.
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.
Despite being set in 1962, when Strickland proudly drives his new '62 Cadillac Sedan deVille on the street, the occupants in the car next to him are driving a '63 Pontiac Convertible. There is a further car goof later when the Soviet plant, Dr Hoffstetler, leaves his apartment for the last time - there is a white '63 Ford parked in front of the building.
In 1962, streetlights would have been mercury vapor lamps, with their characteristic greenish-blue-tinged light. Sodium vapor streetlights were not developed until the beginning of the 1970s and not widely used until the later part of that decade.
The dial tone and ringing tone heard in the phone at Zelda's house were not accurate. Dial tones and ringing tones of that era were more like buzzing sounds rather than the multi-frequency tones heard in the movie. Those are the tones used in modern landline phones.
The exterior of the lab was filmed at the University of Toronto Scarborough Campus, built 1963-1965 with Brutalist architecture style, which was new to the US and Canada, but the interior looks old and worn.
Early in the film, we television sets on sale in a shop. The images on the screens are of a helicopter and a B-52 bomber. If they represent footage from the Vietnam War, this would be anachronistic because B-52's were not used in Vietnam until 1965.
On one of the first scenes of the movie, the compact range seen in the kitchen boiling water is a 1966 Frigidaire RG-22K, a Canadian model made in Scarborough Ontario that was never sold in the United States or before 1965.
When Giles asks Elisa to turn off the TV because he doesn't like what's being shown, some of the footage appearing on the screen is of civil rights protesters being attacked by police dogs and sprayed with fire hoses. The most famous incident of such police attacks on civilians-and the likely source of the footage-was in Birmingham, Alabama, but it happened in May 1963, the year after the movie took place.
The TV set in Giles's apartment- with it's large rounded-end picture shape - is a Color TV appropriate to the year. However, back in 1962 that was a relatively rare and expensive item likely to be found found only in a high-end home. The set in Strickland's home, with its squared-off B&W tube would have been more appropriate for Giles and vice-versa.
When Strickland sets his cattle prod on the bathroom sink the prod is at an angle to the sinks for a few shots. Then when Elisa approaches the sink the cattle prod has moved, it is now parallel to the front of the countertop.
When Hoffstetler is done filling the syringe with the lethal fluid there is just a little bit of fluid in the syringe. Later, when he takes the syringe out of his pocket to inject the MP in his neck, there is much more fluid in the syringe.
In the bathroom scene with Strickland, Eliza and Zelda, there is a brief long-shot of Strickland picking up his cattle-prod and some blood remaining near the sink. In the close-up when Eliza notices the blood, the amount of blood has apparently increased.
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.
When Strickland (Shannon) drives home from the dealer's with a new Cadillac, the car has a regulation Maryland license plate. A temporary cardboard plate would have been issued for the first couple of weeks of ownership.
As the Strickland family watches "Dobie Gillis" on TV, the son asks if they can watch "Bonanza". The two TV series were never on opposite each other: "Bonanza" was on Saturday or Sunday (depending on the year) and "Dobie Gillis" was on Tuesday nights.
Michael Shannon's office includes racks of CCTV monitors, as well as Tektronix 520 Vectorscopes. Vectorscopes are used exclusively with color TV cameras, recorders, etc., and would have been of no use with the black-and-white cameras and monitors used in this facility.
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.
Based on references to missiles in Cuba, the action takes place in last half of 1962. However General Hoyt says he has known Strickland since Pusan "thirteen years ago". The battle of Pusan was in fall of 1950, not 1949.
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.
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.
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.
In the beginning of the film Eliza's scars are on the right side of her neck. In the final scene they are on the left side of her neck. Actually, Eliza has scars on both sides of her neck (because they're actually not scars but gills). You just only ever see them on one side at a time, depending on where the camera is placed.
When Strickland is driving his car to Elisa's house by the theater, his car is normal without bumps in spite of being crashed during the earlier escape. However, Strickland is not driving his car in that scene. In an earlier scene, Strickland and Fleming are staking out Dr. Hoffstetler's apartment. When Hoffstetler comes out, Strickland orders Fleming out of the car, to which Fleming answers "But this is my car". Therefore from that point on, Strickland drives Fleming's car which is undamaged.
After Dr. Hoffstetler is shot in the mouth, a gaping hole is left in his cheek. We then see him down on the ground, with his mouth open and a bright floodlight shining on his face, and yet no light shows through the hole at all.