All scenes at the Vaudeville Theater show the same audience, stock footage obviously from a much earlier film.
In Chapter 1 "Millions for Defense", the steamship shown at sea is not the one depicted as leaving the dock in China. Note the differently-colored bridge area and the markings on the funnels. Yet another ship is shown docking in the U.S. that has three funnels vs. two from the previous ships.
Automobile models in the chase sequences often do not match up, suggesting stock footage from another film.
Stock footage of Market Street in San Francisco is shown, but new filmed exteriors are obviously those of Los Angeles; the actual identity of the city is never mentioned. Stock footage of Chinatown does not match up with newly filmed footage.
In Episode 5, "Desperate Chances", the locomotive of the train Red jumps on is #445, but the one showing pulling off on a siding is #971 - and it has different cars behind the engine.
There is no way that Mannix could be disguised as Quong Lee. Mannix is a larger figure, whereas Quong Lee is a smaller figure with a narrow face. His voice is also completely different.
In Episode 4, "High Stakes", when Red is in the car chasing after two men, one of them shoots at him. White smoke in front of the car's windshield is used to indicate a hit, but the attempt at masking the jump cut fails as the smoke instantly disappears when the bullet hole in the windshield appears. This same goof appears in Episode 12, "The Enemy Within".
In many car chase scenes in this series, tires are heard squealing while on dirt roads.
In Episode 11, "Heavy Odds", when Mannix gets back to his office, the secret panel starts to go down before his pushes the button behind the picture on the wall.
In a lot of car chase scenes in this series, the producers have nixed rear-screen projections in close-ups of characters while they are driving in favor of just blank walls behind them - sometimes with the cars throwing shadows on the wall.
In Chapters: 6 and 7, Vane (Hugh Huntley) standing in front of a bullseye target appears transparent in portions of the scene.
In Chapter 1 "Millions for Defense", the passenger liner depicted as leaving China for the U.S. is the Japanese steamship Nagasaki Maru. This is highly unlikely as Japan was at war with China at the time.
In Episode 4, "High Stakes", after Natacha makes a phone call backstage at the theater, a moving shadow of the boom microphone is visible on the wall, upper right of the frame.
In Episode 11, "Heavy Odds", when Mississippi has the drop on Weaver, a shadow of the boom microphone is visible to the left of his head.