Revealing mistake: When a yellow cab pulls up to the curb, it is obvious that the street is part of a studio backlot and not a real city street because the businesses have no names. The sign outside one building says simply "Tobacco." The diner has only the word "Restaurant" painted on its windows. Another business has no identification other than "Fish and Poultry" painted on its window.
Continuity mistake: When Jeannie is on the settee talking on the telephone, the cord is missing in some shots.
Factual error: The film begins in 1860, but the majority takes place 20 years later, so 1880. When James Rankin obtains files on the Haymarket Strangler/Edward Styles case we are shown another box labelled with details about Jack the Ripper, who wasn't active until 1888.
Plot hole: Jean Simmons is supposed to actually be correct about her husband being in love with his sister in law, and not insane. When she enters the nightclub acting weird, in a dress too large for her and hanging off her, exposing her brassiere, she is completely out of character. She is not drugged at this point, as she stopped drinking the paraldehyde before this.
Other mistake: Outlaws are chased by a mounted posse. One outlaw up on a hill shoots two of the posse members from long distance. Next shot, the two injured posse members are lying on stretchers and the chief deputy orders someone to go back to town and get a wagon. The stretchers were canvas, wooden handled, military style. Where did they come from?
Continuity mistake: When Diestl and Hardenburg attempt their wild dash to the coast on the motorcycle, they pass the same wrecked Kubelwagen three times.
Continuity mistake: When Daffy rushes up to take his breakfast from Elmer, you can see the door behind them is closed, but when Elmer tells Daffy he's had enough, the door is now open.
Continuity mistake: When Sylvester sucks the spaghetti into his mouth after thinking he has captured Tweety, you can see bowl next to him is full of spaghetti, but when he is clobbered on the head by the mallet, the bowl is empty.