When Fred is on the porch in the beginning, the studio walls can be seen without any backdrops. Same thing when Betty Aberlin arrives and departs.
Within the first several minutes of the program, Mister Rogers' microphone is clearly misplaced. With his every move, the microphone-on-sweater static is present in the audio.
As Mister Rogers and Betty Aberlin walk into the kitchen to get the balloons, the boom microphone is visible as it follows them along the way.