Plot hole: Dr Kepple is finally caught when he rushes to the hiding place of the calibration converter that he hid in the lamp after the murder. Why is it still there? It was a great hiding place initially when the police were searching people and the building in the hours after the murder but Kepple had plenty of opportunities after that to get rid of it. It is the only piece of evidence linking him to the crime and it is in his office so you would think that his main priority would be to dispose of it as soon as possible.
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.
Continuity mistake: Columbo is eating with the commandant of a military academy. Columbo has carrots on his plate, among other things. A few shots later, the carrots have been replaced with beans. The next time the plate is seen, it has carrots on it again. Later on in the same scene, the beans are back. Finally, at the end of the scene, there is a longer shot as the commandant is leaving the table, and where the vegetables were there is now something that looks like meat. (00:36:05 - 00:42:45)
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.
Plot hole: In the last scene Columbo convicts Hanlon of murder by playing back the recording of Hanlon's final call to the victim Wagner (the phone-box call near the crime scene is Hanlon's alibi. He is pretending to be in his VIP-box in the football stadium, which is too far away at the time he murders Wagner). The point is that the recording is missing the loud clock chimes from a little clock inside the VIP-box, which means Hanlon's alibi is "destroyed", he was not in his VIP-box, he must be somewhere else at that moment. Problem is the missing clock chimes are not hard evidence. Hanlon could say the clock was not working that day or the battery was empty and so on. Beside that it would be much easier to catch Hanlon if Columbo would check the outgoing phone calls asking the telephone company.
Plot hole: Just before Joe Devlin kills Vincent Pauly in the hotel room, he picks up the Full's Irish Dew whisky bottle with his bare hands. The same bottle falls to the floor when Pauly is shot, and Devlin then kicks it over to the body. Devlin didn't wipe the bottle clean at any point, therefore it will be covered in his fingerprints, but this is never mentioned throughout the episode. There's no way the police would overlook such a basic clue.
A Deadly State of Mind - S4-E6
Other mistake: Right before Columbo tricks Doctor Collier into incriminating himself, he places Collier under arrest, even showing him the warrant. At no time does Columbo inform Collier of his Miranda Rights; meaning that Collier's self-incriminating statements would not be admissible in court. Although the series typically features Columbo cornering the culprit in a way that is unlikely to hold up in court; this particular example stands out as Columbo has torpedoed his own case. If he had not placed Collier under arrest and let him incriminate himself then the statements (in front of witnesses) would be admissible as evidence.
Continuity mistake: At the end, when Columbo is demonstrating on the mannequin, his cigar changes position between shots.
Continuity mistake: Dr. Murcheson is not wearing gloves when he scrapes the women's faces. Then he goes into another room and removes a gray glove from his left hand.
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.
Columbo and the Murder of a Rock Star - S10-E3
Factual error: They talk about Wednesday as day of the murder. On the other hand, we see a speeding ticket with 3-11-91. In 1991, March 11 was a Monday and November 3 was a Sunday, so whichever way the date is written the day is wrong. (01:17:53)
Columbo and the Murder of a Rock Star - S10-E3
Factual error: Champagne corks have a metal cap between the cork and the wire cage. (They can be seen when both Creighton and Columbo open bottles.) When Creighton injects the chloral hydrate into the champagne, he does not have the difficulty he should have getting through the metal. The needle does not come out damaged as it should, and it did not go far enough into the cork to put the liquid into the champagne-it would get lost in the cork itself.
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."
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.
Visible crew/equipment: The Great Santini makes a vase of flowers appear on a table. Before he holds up a cloth to conceal the vase as it appears, the tips of the flowers can be seen beyond the far edge of the table. As he pulls the cloth away, there is a quick glimpse of the hand of the crew member who put the flowers on the table. (00:11:00)
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.
Make Me a Perfect Murder - S7-E3
Continuity mistake: When Kay retrieves the gun from the elevator ceiling, they switch shots several time looking up at the ceiling and down from the ceiling. In one shot looking up, the barrel and grip of the gun are over the edge of the ceiling tile. In the next down shot, just the barrel is near the edge and the grip is inches away. Back to an up shot and the gun returns to barrel and grip over the edge.
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.
Suggested correction: He very likely will. As we've seen, Columbo is very thorough. The missing clock chimes aren't meant to be definitive proof, just enough to warrant an arrest. Columbo will continue to work the case and gather evidence.
Columbo will continue to work the case and gather evidence? Well with that sentence they could stop every Columbo episode after 5 minutes. Hey guys, Columbo has nearly nothing against the murderer but he will continue to work the case outside this episode be sure.
It's the detective's job to investigate the crime and gather sufficient evidence to warrant an arrest and potential conviction. Yes, this would apply to every episode, and yes it applies to all detectives. Many of Columbo's investigations result in him using circumstantial evidence to arrest the killer. In one episode he arrests a man based on how the victim's shoes were tied. That wasn't his only evidence, however. In many cases a preponderance of circumstantial evidence is enough.
It's a TV show, Columbo was made for entertainment, not to be used as a script to prosecute a potential criminal.
No judge would allow this "evidence" to even be presented to a grand jury. Just because Hanlon wasn't in his booth at the time doesn't mean he was at the murder scene.