Chadwick the tailor puts his glasses on, then in closeup, the glasses have disappeared. Returning to the long shot, the glasses reappear on his nose.
Columbo's drawing of the crime scene changes between shots. The most noticeable difference is the X marking the position of the body, which switches between having diagonal lines and vertical/horizontal lines.
When Columbo enters Hayward's office to draw the diagram of the crime scene, the cup with pencils in it on Hayward's desk keeps changing from being knocked over (front shot) to standing up (from behind.)
When Columbo uses the yellow and red car models, he places the yellow car with the "window" (black curved line) facing backwards. In the next shot, the "window" is facing forward.
When the senator walks down the stairs with his PR team, he has makeup protection paper around his neck. The paper is crumpled. Miss Johnson calls him over; he then removes the paper, which is now straight.
When Haywood fires his gun into the wall, it's a silenced revolver. Revolvers cannot be silenced using a silencer. That only works on automatics or semi-automatics.
After the newscaster starts droning out what are obviously election returns - not polls - the candidate and his wife go vote. Voting results do trickle in by precinct, but the trickling doesn't start until after the polls close. Closing time is set by the state and so statewide. If the newscaster is reading vote totals by precinct, and he is, then the polls have closed. Even for a candidate, it is difficult to vote after the polls have closed.
The tailor tells Columbo that there are many shades of brown, for instance, pale brown, tan, and cream. Cream is nowhere near brown. Any painter knows that to obtain cream, one must mix white and yellow; cream is simply an off-white color. A tailor would be aware of this fact.
Nelson prepares an anonymous letter to himself. A cut up newspaper nearby suggests that the letter was fashioned from newspaper cuttings, yet extensive white space surrounding the individual words (in various fonts) reveals that they were individually printed on a blank sheet before they were cut, with no adjacent words or lettering anywhere around them.
When Nelson walks out on his balcony to fire the gun through the glass, the background view of the city behind him is an obvious painting with folds and brush marks.
Even though he is shot in the chest and head, there is no blood on Harry.
Columbo and Mrs. Hayward are talking near the pool as Nelson Hayward is on camera for a campaign ad, reading from the cue cards. His words don't match what's on the cue card which is shown to the viewer as the camera follows Columbo and Mrs. Hayward.
Columbo is reading a newspaper whose articles contain the same 7 paragraphs (variably repeated) used in newspapers featured in 'Lovely but Lethal' two months prior. None of the text has anything to do with the headlines.
Nelson Hayward lights a firecracker on the balcony to make people in the other room think someone fired a shot at him. The detective immediately runs into the room and goes out to the balcony to look for the shooter. He would have easily seen the paper from the exploded firecracker.
At around 1:25 the image on the television screen moves around wildly at times suggesting a superimposed image that was not quite synchronized.
Hayward does not initially completely shut the safe door and yet a loud "clank" is heard.
The road traveled by Columbo in the tow truck is impossible. When Columbo leaves the beach house, the ocean is to his right. It is still on his right as he later drives along the beach. After he stops short of the highway to check the stop watch, he turns right onto the highway, and the ocean is now on his left.
When Columbo and Hayward are discussing the possible angle of the shooting, neither one considers whether there might have been two people in the following car. In this scenario, the driver parks offset as shown, illuminating Stone, while the passenger gets out and shoots Stone.
Although Columbo takes the suspicious bullet out of the drywall, the hole is still no bigger than the size of the entrance hole.
Boom mic shadow moves about Columbo's hair when talking with Nelson about getting a jacket for Saturday.
The shadows of the boom/microphone appear on the inside of the front door when Mrs. Hayward lets Columbo in the first time.
When Columbo is having his vehicle inspected, he turns on the windshield wipers and notices that one wiper is not working. The reflection of the boom can be seen in the upper right corner of the windshield.
When Columbo is stopped for a vehicle inspection, he asks two highway patrolmen for directions to "Ridgeway Drive," but the second patrolman (Jude Farese) answers with directions to "Ridgewood Drive."
Just as the commercial crew is about to start the recording, an airplane is heard in the sky. The crew would normally stop the recording as it would be picked up by the microphone.
The commercial crew would have told Columbo and Mrs. Haywood to be quiet much sooner when they are whispering while the taping was going on. Even when they moved away to the nearby table, they likely were too close and their conversation could have been picked up by the microphone.
The commercial director would not have been the person to use the clapperboard prior to shooting the ad. Another crew member is walking around with it earlier. He would have been the one to use it.