Factual error: In scenes from the oil rig there are shots that show the shore line. This oil rig is supposed to be offshore of Louisiana. However, mountains can be seen in the shots of the shoreline. There are no mountains in Louisiana.
Mercy Moment Murder Measure - S1-E7
Factual error: Early in the episode, there is a long shot of Woodhull's farm, snow on the ground...and aeroplane vapor trails in the sky.
Factual error: Throughout the series, there are scenes of decapitated heads speaking with audible voices, in spite of the fact that they have no diaphragms, lungs or larynxes. Even if a decapitated head was somehow fully animate, it still couldn't utter a sound.
Factual error: Bellamy tries to fire his assault rifle twice, but because of a dud round, it fails both times. There is an audible click each time he tries. The first attempt there would be a click, because the firing pin was charged when the last round was ejected. However, without that charge either automatically when a round is ejected or manually pulling the charging handle, the second attempt would have been silent since the firing pin was not engaged. (00:35:45)
Factual error: They repeatedly say how equipment will freeze in moments, but they leave their faces exposed and coats open, hoods off at times. In such cold temps, the skin would freeze in minutes.
Factual error: Sir Malcolm tells Vanessa to wear a facemask when they go to minister to the poor as cholera is rife in the area. However, the series is set in the 1890s and it had been well-known since the 1850s that cholera was caused by contaminated food and water and not by airborne germs. As an educated man, Sir Malcolm is bound to know this.
Attack on Central City - S3-E14
Factual error: Wells states that there are "precisely 90,000" possible 5-digit combinations for the keypad (to abort the nuclear code). However, there are actually 100,000 possible combinations (10^5).
Chin Check - S1-E3
Factual error: The cops raid a house and find some rifle ammunition. The female cop says "cop killers." A few seconds later three cops are looking at the bullet and a box used to store it, it appears to be a 5.56x45mm round used in the AR-15 style rifles. All high powered rifle ammunition, doesn't matter if its bullet is fmj or armor piercing will go through soft armor which is what all police officers wear. Such ammo is available to civilians in every store. All rifle ammo could be considered "cop killer." (00:03:50 - 00:04:56)
Occultation - S1-E6
Factual error: Eichhorst seems to be unsure what his SS rank is. He is addressed as Standartenführer (Colonel) but wears the epaulettes of an Obersturmbannführer (Lieutenant-Colonel) and the collar patch of a Sturmbannführer (Major). In addition, his other collar patch bears the standard SS lightning runes instead of the death's head of the Totenkopf concentration camp personnel.
Factual error: Peggy and Ed are hiding out in a cabin "just outside of Sioux Falls," but are somehow also close to Mt. Rushmore. Mt. Rushmore is near the western border of SD, Sioux Falls on the eastern border, more than 340 miles apart.
Factual error: Henry states that the car bumper of an 2007 'XJ' is a certain height off the ground and led to a particular injury to a dead person. He claims he knows this because he is a Jaguar enthusiast. He then points to a photograph of the 'New York Kids' in a pre-2002 Jaguar XKR as 'circumstantial evidence' that it was this car that caused the injury. A Jaguar enthusiast would never mistake an XKR for an XJ.
Factual error: LaSalle's 2015 pickup truck is shown with a green Louisiana license plate. Those plates were only distributed in 2011 and 2012 in celebration of Louisiana's Statehood bicentennial. Furthermore, pick-up trucks in Louisiana are always provided with basic seven digit plates with only the state name, the digits, and the state motto Sportsman's Paradise. The vehicle owner could request a vanity plate with a specific order of digits, or a sport's design, but again, the state hood could not be one.
The Legend of Curtis Ballard - S2-E3
Factual error: In the first flashback scene of Ballard serving a Mormon mission in Lithuania, he laments that he has been on his mission for 18 months and has yet to baptize a single person. In a later flashback scene when he and his companion are visiting the prostitutes, he states that he and his companion are 19 years old and they should be in college, going to parties, getting drunk, getting laid, etc. Instead of serving missions. These scenes take place in 1991, at which time young men did not serve missions for the Mormon church until after they turned 19, so if Ballard had already been on his mission for 18 months, then he should have been at least 20 years old, and closely approaching 21.
Factual error: The address on Lee's business card shows her zip code for Atlanta, GA as "11453." This is a non-existent US zip code, and the zip code for Atlanta is "303xx."
Factual error: Throughout the episode the military are shown carrying Israeli Military Industries Tavor assault rifles. Israel does not sell weapons to any Arab states. Especially if said state already allied with the US and is thus buying its weaponry from the US.
Factual error: Simone is hit by a bus running after her niece. The bus is service number 106, however service 106 is Finsbury Park - Whitechapel and runs nowhere near Horseguards Parade, which is where the scene was filmed. Also the bus is operated by Sullivans Buses, when route 106 is actually operated by Arrivia. The depot code SM (seen on side of bus) is Potters Bar and not AE (Ash Grove) which is the actual depot that operates route 106.
Factual error: The men rowing the longboat into the wharf at Nassau are completely hopeless oarsmen. Needless to say, 18th century sailors would have been expert oarsmen. Untrained 21st century actors are not.
Sea Change - S3-E1
Factual error: President Dalton's memorial US Flag in his office is folded wrong and displayed upside down in the flag triangle. The US Flag is always displayed with the stars pointing up. (00:47:00)
Things Were Different Then - S4-E16
Factual error: The car is referred to as a '73 Cadillac Eldorado. It has square headlights, and therefore is a '75 or '76.
Factual error: Constantine's driving licence is shown - it's a UK licence, but no. 7 where his signature should be is blank, and no. 8 where his full address should be simply says "England, United Kingdom." Both are printed onto the licence when it's issued - without that info it would never be issued in the first place. And it's not a fake, because why would he have a fake licence with his real information on it? It's just an incomplete prop.