In spite of the explosion in Eddie Kane's apartment loud enough to be heard from a distance there was very little damage done.
Just before the manuscript service arrives, Columbo is drinking from a red plastic cup, like a thermos top. When the man arrives and Columbo speaks to him, the cup is gone. Even after he rises from his chair and spins it around so the desk top comes into view, the cup is nowhere to be seen.
In the opening scene, when the explosive strikes the car windshield, it is thrown from the left side of the vehicle, but in the closeup it strikes as if thrown from directly in front of the car.
Riley Greenleaf met Eddie Kane at 22:00, drugged him with the champagne, typed a synopsis, then learned how to make a bomb from scratch. The explosion killed Eddie Kane. Using an educated guess, the explosion would happen no earlier than 22:30.
The scene was then switched to broad daylight, when Columbo got into a restaurant, had lunch and questioned Mr. Neal and Ms McCray. When he finished his meal, he received a phone call about the homicide (of Eddie Kane).
From lunch time to 22:30, it takes at least 7 - 8 hours even if it's a late lunch. There's no way Columbo spent 7 - 8 hours in the restaurant before he received the phone call on the homicide.
Is it possible for the police to go to the crime scene the next day? not possible, as the next scene showed Eddie Kane's house at night time again.
The scene was then switched to broad daylight, when Columbo got into a restaurant, had lunch and questioned Mr. Neal and Ms McCray. When he finished his meal, he received a phone call about the homicide (of Eddie Kane).
From lunch time to 22:30, it takes at least 7 - 8 hours even if it's a late lunch. There's no way Columbo spent 7 - 8 hours in the restaurant before he received the phone call on the homicide.
Is it possible for the police to go to the crime scene the next day? not possible, as the next scene showed Eddie Kane's house at night time again.
Although Greenleaf's publishing company is located in Los Angeles (where Columbo works), a cover letter is addressed to him in New York City.
When Columbo opens up Eddie Kane's address book to look at Greenleaf's number, the closeup is the same one as the earlier shot when Greenleaf did the same thing, including Greenleaf's latex gloved finger.
When Columbo is in Mariette Hartley's apartment showing her the typed synopsis (of the murder victims's book) there aren't any creases in the document from which she is reading, whereas, immediately prior in Jack Cassidy's office (retrieving it from the wall safe) there are three visible folds in the synopsis.
Between the opening sequence where Greenleaf meets Eddie, to the faked parking lot accident, and when he is discovered by cops parked in a park, the car Greenleaf is driving is a 1969 Cadillac Coupe de Ville convertible. At his house, when Columbo looks out of a window at the car in the driveway, it's a 1967 model. When they go outside for Columbo to check accident damage, the car is again the original '69.
In the opening scene, when Eddie is talking to Riley, Eddie's line "Wanna synchronize watches" is obviously edited into the previous voice track. There's an unrealistic small-room echo on that line.
(at around 37 mins) The camera pans the high rise where Riley Greenleaf's office is located. The episode (and the series) is set in the Los Angeles area, but the high rise pictured is the Bank of America world headquarters in San Francisco (featuring the black marble "Banker's Heart" sculpture in the plaza in front of the building) located at California and Kearny Streets.
The lawyer, David Chase, scolds Columbo for suspecting Riley Greenleaf without evidence. There was evidence: the murder weapon registered to Greenleaf and bearing his fingerprints.
The murderer, until then very cautious, lights a cigarette while writing the letter and burns his car's tires near the victim's house; two possible clues left for the police to find.
David Chase says, "When are you police going to realize that it takes more than circumstantial evidence to convict a man of a crime?" Convictions based solely on circumstantial evidence can and do happen in real life.