Pompeii's Gate to Hell - S4-E8
Factual error: This episode includes a segment about an abandoned dry dock in San Francisco. At one point, one of the commentators several times refers to the U.S.S. Ward as a "battleship," and marvels that it was built in 17 days. The Ward (DD-139) was a 1200-ton destroyer, not a battleship, and was launched after only 17 days, but then took another two months to complete. By way of comparison, the California (BB-44), an actual battleship of 32,000-tons built during the same time period, too nearly five years to complete.
Episode #1.4 - S1-E4
Factual error: In 1940, all the Americans are leaving London on transatlantic flights. Although the first commercial transatlantic flights began in 1939, they were suspended on the outbreak of war. Real commercial transatlantic service did not begin until after the war.
Continuity mistake: Near the end of the episode when Nico is burning the photo of her father, she burns it at the top left corner in a close-up shot. Then in the following shot the photo is suddenly burning at the top right corner instead.
Episode #1.3 - S1-E3
Audio problem: Elaine refers to someone's "ChatsApp" account, but her lip movements show she is actually saying "WhatsApp." (00:13:55)
Factual error: The provincial police is always described as the Ontario Police Department (OPD) instead of the correct Ontario Provincial Police (OPP).
Audio problem: Right after Carol finishes studying by singing a rap to Katie, Katie congratulates her and Carol hurries out. They exchange several lines of dialogue, but it all appears to be dubbed. During most of the dialogue, each character's mouth is not shown when they speak. However, the cadence of Katie's moving jaw can still be seen from behind, and appears to last longer than the audible speech. Additionally, Katie and Carol can each be heard to speak when it can be glimpsed that their mouths are not moving.
Continuity mistake: The way "Jack Griffin" is written on the board changes in various shots.
Deliberate mistake: The police force in the town is the Gendarmerie, the standard issued firearm is the Sig Sauer P2022 in 9mm. The police officers on this show carry a Beretta and not the 9x19mm one which is the model 92fs, they carry a never issued Beretta 84 chambered in .32 acp or 9mm short. Plus they use some weird holster where the gun arches out and hangs low like a cowboy holster and dangles around. Easy for a suspect to gain control of the officers gun and this happened in this episode.
Character mistake: One of the characters, Agent L, is usually talking to the kids via some gadget with bad audio. In The Golden Gauntlet, the first time she appears on the screen she misnames Agent J, calling him "Agent G." She then later in her speech calls him by his name correctly.