Just before the judge explains the purpose of a preliminary hearing, there is a radio or intercom device on the bench just to his right. Lt. Tragg is immediately called to the witness stand and after the fade to
Tragg on the stand, the device is gone and a water pitcher and glass are in its place.
In Evelyn Bagby's apartment in scene one, (at 01:45) there is no entry button to buzz open the building's door. When Mason visits her at 17:43, there is still no entry buzzer. But, at 19:12, a small square box with a white button has appeared next to the front door intercom which Evelyn pushes to admit Tragg to the building.
The exterior scenes outside Evelyn Bagby's apartment took place at night, but were obviously shot in the daytime. This is the first of many clumsy examples of day-for-night shooting that would occur during the series.
During his conversation with Helene Chaney, Perry's reaction shots were obviously done on a featureless sound stage.
At 12:10 you can see the characters mark on the floor, an upside-down T, to mark where the character, Della Street, is to more to and stand for the shot.
At the approx. 24 min mark, when Perry is waiting outside the Studio door for Ms. Chaney, you can see the reflection of the camera, lighting, and a crew member on the trunk of Perry's Fairlane.