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.
Short Fuse - S1-E7
Continuity mistake: While riding in a chauffeur-driven car, Mr. Buckner wants to smoke a cigar. He picks up a wooden cigar box. The lid is secured by two pieces of black tape. He peels up one piece of tape. After a close-up of his face is shown, he peels up the second piece of tape and the first piece is now back in its original position across the lid.
Factual error: When Columbo initially latches onto the radio dilemma (which ultimately solves the case) the dial is tuned all the way to the left. He later tells someone that the radio is set to 'Classical 52', but an AM radio starts at 54, meaning 540KHz. There is no 52.
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.
Short Fuse - S1-E7
Continuity mistake: In the cable car climax, Roger opens the cable car door to throw out the cigars. Then while he is scrabbling on the floor, and there is dialogue, the doors are shut. Then, at the end, the doors are open again.
Dead Weight - S1-E4
Continuity mistake: Helen Stewart and her mother are boating in the harbor and are about to pass a small island. A Marine colonel goes to the nearby home of a retired general to inform him that he is under investigation for cost overruns on a government contract, Fearing that the colonel will implicate him, the general shoots and kills him near a window. Helen is looking toward the home and witnesses the shooting. She tells her mother, "We have to go back." The boat is in the same position it was in five minutes earlier.
Continuity mistake: The witness dunks the strawberry in the white sauce while talking. We cut to a view in front of her, and the dialog continues but suddenly the strawberry is half-eaten. When did she take that bite? (00:41:40)
Continuity mistake: When Columbo is eating his chili in the booth at the diner, whilst talking to the daughter of the murderer, his bowl of chili moves. It is right in front of him at one point but is then away from him. And it now contains less food.
Short Fuse - S1-E7
Continuity mistake: When Buckner's car leaves the chemical plant, it's a stretch limo with three bench seats. When it explodes on the mountain road a few scenes later, it's only a two-seat limo. (Buckner, who was initially in the distant rear seat, is suddenly close enough to reach up and take the cigar box the chauffeur hands him from the front seat. The entire middle section of the limo has disappeared.) (00:13:40 - 00:15:30)
Factual error: To make a call, Mr. Bremer enters a seven-digit number on a push-button telephone. The first three keys he punches are 1, 2 and 4. No telephone number in the United States begins with a 1.
Continuity mistake: When Columbo and the woman have finished flying in the light aircraft, she taxis the aircraft back and shuts down the engine. There isn't much to see behind the aircraft at this point, but when Columbo and the woman get out (in the immediate next shot) there are two rather large buildings/hangars which have magically appeared right behind the aircraft. Plus the aircraft propeller has changed to a more horizontal position.
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)
Deliberate mistake: Beth shoots Bryce three times in the chest, and he falls face down on the floor. She then drags his body across the floor, also face down, to in front of the sliding door, but there is no sign of blood anywhere.
Suggested correction: In the early Seventies, no television show used blood effects. They were too expensive and would severely restrict potential audiences as television channels were notoriously conservative in those days. This is a creative and technical decision, not a mistake.
Dead Weight - S1-E4
Plot hole: How did the revolver get into the museum after the murder? Falk said he did not see it in the packing crate.
Continuity mistake: The insurance agent has a complete hot dog in his hand while Columbo talks. When we cut to a view over his shoulder, Columbo's sentence continues but the agent is suddenly chewing. When did he take that bite? (00:36:20)
Factual error: When Mrs. Williams takes Columbo flying, she does some aerobatics. Neither of them is wearing a seatbelt. No pilot would do that.
Short Fuse - S1-E7
Continuity mistake: As Roger helps Columbo remove the pink Silly-String from his hair, the amount and configuration of the string differs radically with each change of camera angle. (00:37:30)
Continuity mistake: In the living room of their home, Lesley Williams shoots her husband in the chest. As he falls, he knocks a lamp off a small table. Lesley puts the lamp back on the table, but in all the following scenes in the living room the lamp is gone. (01:00:00)
Dead Weight - S1-E4
Other mistake: Columbia calls Helen Stewart from a pay phone. He dials only six numbers, not seven.