Goofs

The card that Sarah Demay left with the pawnbroker lists her address as: 334 Lee Street - Apt. 204. Yet, when she opens the door for Voss, the door clearly has the number 203 on it. In court, Brenda Larkin refers to the address correctly as apartment 203.

After preparing to cause an arson fire in his private office, Voss carries the gasoline can into the outer office where Demay is working. There is no reason for Voss to move the gasoline can, and the sight of such an incongruous object in Voss's hand would obviously arouse Demay's suspicion at once. Update: Voss may have moved the gasoline can into the outer office to more completely incriminate Demay. Also, Demay was not watching Voss when he exited his office.

When Perry Mason is in Ms. Larkin's home, the light switch on the wall is in the off position but the lights are on.

Demay was using some sort of solvent to clean the tapestry, and the smell of the solvent, which was right under his nose, could have prevented him from smelling the gasoline. Not likely in an actual occurrence, but on TV - well.

When Voss carries the gas can into the work area where Demay is working, not only is it odd that Demay didn't notice Voss carrying the gas, but a gas can that has gas in it, or even if it had all been emptied out, carries an odor with it. Gasoline has a high vapor pressure, and walking into a room with a gas can, even empty, should have been detected by Demay. Especially since Voss had been spreading it around the other rooms. He would have it on his hands and the outside of the can. An example of this would be: smell your fingers after gassing up your car. Even without any splashing on you. You still have the scent of it on your fingers and hands.

In more than one scene, Perry's shoes are noticeably squeaking. This could be classified as a character error. A suave guy like Perry Mason wouldn't put up with a defective pair of shoes.

When Voss sets up the arson, he lights a candle and uses it as a delay mechanism so he can establish his alibi. After lighting the candle, he blows out the match (wooden) and immediately tosses it to the ground in the same area where he had dripped the gasoline. In all likelihood, the wooden match, while not actually burning with a flame, would have still been smoldering, and thus would have ignited the gasoline just dripped on the floor.

Hamilton Burger mispronounces Theseus as "thesis."