Goofs

The film starts with the left projector. When the reel is over, Walter turns on the right projector. When Kay manipulates the counter, it's suddenly the left projector that is running. When Kay returns from the murder, the counter of the left projector is off although it is still running.

When Kay Freestone departed the projection room, she left the door half open. When she returned after committing the crime, the door was closed.

As Columbo questions Kay for the first time, he fumbles with some pieces of paper and a notebook, unable to find what he seeks as he puts the items on a desk. He goes through his pockets once more then picks everything up and walks away. Again wondering where the piece of paper is he is looking for, he returns to the desk where his pieces of paper and notebook are back atop it.

When Kay is listening to her recorded timer the first time the recording says '30 seconds to go', but when she is committing the crime the recording says just '30 seconds'.

Columbo has already been told of the technicalities of changing the reels in "Double Exposure".

When Columbo is at the TV repair shop, the TV repairman is working on Columbo's TV while the TV is on and Columbo is watching it. An intelligent person would never replace parts in an electronic device while it is plugged into a power source and powered on; that's asking for death by electrocution. Certainly no professional who fixes electronics for a living would be elbow-deep in the electronics while it's plugged in. But he would have to have it turned on in order to troubleshoot the problem. You can't measure voltage and current with the set turned off.

Kay retracts and extends the radio antenna very easily, thus the extended antenna wouldn't remain extended when she uses it to raise the ceiling light panel in the elevator - it would retract under the weight of the panel.

The operation of the Video Control Room equipment (in all such scenes) is inaccurate. 1) Professional equipment such as the Video Switcher Control panel does not have on/off switches. 2) The four camera monitors at the bottom would be fed by direct signals from the cameras and no control would change them. 3) There would be no function to create sine wave patterns. 4) In several shots of the screens, optical masks can be seen where the images were added in post-production.

Kay Freestone must have expected the murder weapon to be found; otherwise, she would not have worn the glove. Yet, when the gun is visible in the elevator ceiling, she removes it. But actions, wearing the glove and removing the gun, are want untimely incriminate her.

The image of Columbo's car sitting in the parking lot can be seen reflected in the glass of the CNC building as Kay enters it before she commits the murder.

Just before his fender bender, one can see that Columbo's car is already damaged before he is rear-ended. (This presumes it was meant to be undamaged before struck.)

Some white light obviously coming from on top of Kay and Columbo when they are supposed to be lit by the candle.

The murder weapon is a self-loading pistol. When it's fired, neither does the slide move nor is a spent casing ejected.

The video control board operator's hand hits the mic as he moves his hand off the board.

Columbo's jalopy car gets rear-ended in an early scene, but the vehicle shows the body damage a moment before the accident.

Most of Trish Van Davere's dialogue is overdubbed by herself. The room acoustics don't match with Columbo's and other actors. She overdubbed in a studio.

When Kay and Columbo are in her childhood home, her line referring to the "voices in [his] head" is different in audio quality and doesn't quite match up with her lips, having obviously been re-dubbed in post-production.

As Columbo and Kay are leaving Kay's new office and they are waiting for the elevator, the boom mic is seen changing positions.

In reality, the crime would be solved immediately when the police tested everyone in the building for gun shot residue.

A perspicacious and attentive detective like Columbo should have noticed the flashes when going to watch a movie, notwithstanding that it is (or rather was) a well known projection technique.