Character mistake: Art expert Dale Kingston describes Goya as 'the penultimate artist'. "Penultimate" has nothing to do with greatness or artistry, it means second to last, and nowhere during his speech does he indicate that Goya is 'second to last' in anything to do with the discussion. In the context he uses it the word is completely meaningless.
Character mistake: Columbo explains to Hayward (the killer) how the accepted version of events is impossible, because when he was shot Harry Stone was standing in a dark garage and the killer could not have angled the headlights of his car in such a way that he was made visible (in order to be shot). But neither he nor Hayward even consider the possibility that the killer could have been carrying a torch, which would not only have illuminated the scene, it would have dazzled the victim and hidden the shooter.
Character mistake: Columbo discusses the murder of Jennifer Welles with Alex Benedict - who killed her - and he reveals that the odometer reading of Benedict's car showed an extra nine miles despite the fact that it was supposedly immobilised in a garage on the night of the murder. Benedict challenges Columbo, saying that he assumes that he has established the distance between the garage and Jennifer's apartment. "Yes, sir." says Columbo. "Exactly nine miles." Since the murderer would have had to have driven to and from the garage to the scene of the murder - the car was back in the garage when the police searched it the next day - shouldn't he have said "Exactly four and a half miles."?
Any Old Port in a Storm - S3-E2
Character mistake: Adrian Carsini, a wine connoisseur and winery manager, pours two glasses of wine, one for himself and one for Lieutenant Columbo. Each man puts his hand around the top of his glass and begins to drink. A true wine connoisseur never touches the top of the glass. He holds the glass by the stem so the warmth of his hand does not affect the taste of the wine.
Dead Weight - S1-E4
Character mistake: When Columbo first comes to the general's apartment, the general is showing Columbo a submachinegun. He also shows him a magazine and says it is an "extra clip." A retired general would know the difference between a clip and a magazine; the terms are not interchangeable.
Character mistake: Piloting a helicopter, Leslie ends a radio conversation by saying "Over and out." "Over" means "I'm done talking; please respond." "Out" means "I'm done talking and I'm ending this communication." An experienced pilot would never say "Over and out." They are two different terms.
Character mistake: Columbo drives to a car lot to question salesman Charlie Shoup. Admiring Columbo's Peugeot, the salesman says, "We don't see many of these. What's it got on it? 20,000 miles? 30,000?" When Columbo tells him "100,000," he replies, "Well, I don't care what's on the speedometer." He meant to say "odometer."
Character mistake: The policeman gets the bag for the ransom from the wife of the kidnapped person, grabs it with bare fingers and puts the money into it - without gloves, too. (00:23:30)
Character mistake: In the performances, Benedict is not conducting; he is waving his arms around.
Character mistake: A valet tells Columbo that automobiles belonging to Sauri embassy personnel are repaired at a service station two blocks away. Later, when Columbo is speaking with Hassan Salah, he says, "I know your cars are taken to a service station three blocks away."
Character mistake: During a rehearsal, conductor Alex Benedict instructs the orchestra to play "quasi un fantasia." Columbo asks Benedict's wife Janice what those words mean. She tells him, "It's Latin for 'like a fantasy." The words are Italian, not Latin.
Character mistake: In the grocery store scene Robert Culp sits on a display of pumpkins but there are 2 signs that say watermelons.
Suggested correction: As a retail worker of 18 years, I know that POS (signage) mistakes happen in supermarkets, for example a product is moved and the correct POS is not replaced. This scene seems to be filmed in a real supermarket meaning this is not a mistake made by the show's producers, however if this was filmed in a studio, "Character Mistake" would be the wrong category as the mistake would have been made by the set designers.
While I've never seen mislabeled items I know mistakes can happen. But since the characters aren't real, every mistake they make is the fault of someone on the crew, whether it's the actor, writer, or set designer. For example, misspellings are considered character mistakes (unless intentional), even though it would have been made by the person who created it.
Character mistake: This episode opens with James Ferris typing the final chapter of a mystery novel. He is using all-capital letters, No professional writer would do that.
Suggested correction: It's not meant to be all capital letters, but block letters. Just look at the title card and credits in the opening - they're block letters too.
Character mistake: After Columbo disturbs Dr. Kepple and his ball goes in the rough, Kepple says they are playing for rather high stakes. He picks up his ball, looks at it, and places it back on the ground. In a high stakes game, that would be cheating, and the other players would not have tolerated it.
Character mistake: Kingsley carries a briefcase in to the attorney's office, but leaves without it.
Character mistake: Columbo took the Beretta off the gun display by inserting a pencil into the barrel of the gun. In a previous episode, he said to NEVER insert a pencil there because it will ruin the groove of the barrel, making it impossible for ballistics to get a match on the bulletin. When using a pencil, Columbo picks up a gun up near the trigger.
Character mistake: When Columbo is in Mr Benedict's house with Mr Benedict, he calculates the cost of Mr Benedict's house at $720,000. A moment later Mr Benedict asks Columbo; "How did you arrive with that figure, $750,000?" (00:43:20)
Character mistake: Twice, Brenner refers to the T-33 aircraft as the Silver Star. The name of the T-33 was the Shooting Star.
Last Salute to the Commodore - S5-E6
Character mistake: After Commodore Otis Swanson is murdered, Columbo goes to the Swanson Shipyard to speak with the Commodore's nephew, Swanny Swanson. Columbo calls him "Mr. Swenson."
Character mistake: Columbo talks to the cardiologist. The doctor gives him information about his patient, Mr. Williamson. Columbo has no warrant, so the doctor is violating privilege. He wouldn't give that information to Columbo.