Stupidity: 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.
A Deadly State of Mind - S4-E6
Stupidity: Collier damages a post with his car as he leaves the driveway. His car would certainly have been damaged. The storyline is not long enough for Collier to have his car repaired. Columbo knows about the damaged post, but he never looks into how the damage occurred and never looks at Collier's car, which would have been incriminating.
Any Old Port in a Storm - S3-E2
Stupidity: Carsini has a wine vault (with very expensive wine in it) with an integrated air conditioner. There are indeed wine vaults like that. But mostly active cooling wine vault are used by "amateur" wine lovers (who can't afford an underground cellar) but not by wine connoisseurs like Carsini. Active coolings are not very reliable. A power failure or a simple malfunction and Carsini would lose all of his expansive wines he collected for many years (like we saw in the episode). So why shouldn't a huge wine connoisseur build a cellar, surrounded by cooling soil where temperatures never rise that high? He is rich, he as a big estate, a villa, and he knows better to store the jewels of his passion adequately. Why store wines in a potential oven where high temperatures (without air conditioning) can even kill a man (his brother) in the first place? It is a far fetched and an unnecessary gambling just to have a murder-plot.
Stupidity: Why does Jack Cassidy plant the lighter in the office when he could just pretend he has forgotten it? Does not make sense.
Stupidity: The cruise ship is sailing from LA to Mazatlan in Mexico. Looking at a map, the ship will hug the west coast on its journey therefore is never far away from land. The murder takes place on the first evening of the cruise only a few hours after setting sail by which time they won't be far from San Diego. Why didn't the captain order the ship into San Diego or another suitable harbour and let the police take over the investigation?
A Deadly State of Mind - S4-E6
Stupidity: In the final scene: Columbo lays a trap for the murderer (George Hamilton). The 'eyewitness' when Hamilton fled the murder scene was a blind man. Hamilton is aware of this. Columbo's gambit depends on Hamilton's assumption that Columbo has coached the witness to act as though he was sighted so as to convince Hamilton that there is evidence against him. In fact, Columbo has the witness' brother, who is sighted, pretend to be the eyewitness and identify Hamilton as the man he saw driving away. When Hamilton falls for Columbo's trap and, believing he is in the presence of the blind man, tries and fails to 'prove' the man can't see. By doing so he reveals his knowledge that the witness was blind, incriminating himself. The problem is, that only a minute or so previously, Columbo had placed Hamilton under arrest, and failed to read him his Miranda Rights. Considering that Hamilton's slip up is the ONLY evidence Columbo has against Hamilton, this was a spectacularly stupid move on Columbo's part. Regardless of how many officers were present to witness this, the fact is that Hamilton was under arrest and had not been advised of his right against self-incrimination; meaning nothing that he said when under arrest can be used against him.
Answer: In the show, he was already a Lieutenant. A promotion would put him in the next rank up, which for the L.A.P.D. would be Captain. However, some of a Captain's duties would be overseeing other officers and ensuring they're compliant with policies, regulations, and standards. It would also most likely take him out of the field. This is something Columbo has no desire for as he rarely goes to police HQ's. Nor does he show interest in compliance and standards (for example, not going to his semi-annual evaluation at the firing range). However, he could still be assigned to a higher pay grade based on expertise, which is a form of promotion that does not include rank advancement. This would be going from Lieutenant I to Lieutenant II. I don't believe in the show it's ever started what his pay grade is. Although, in s02e01 (I believe) he mentions making $11K a year. Whether or not this was a true statement on his part, if you could find pay scale information for an LAPD Lieutenant in the 70's, it could give you an idea of his pay grade.
Bishop73