While many suppose that such test patterns were slides or printed stock that a television camera was aimed at. However, variations in lighting or a misadjusted camera would have service techs and home viewers adjusting their sets to a misadjusted source. Therefore, these patterns came from a monoscope tube, where the image - either the standard generic Indian pattern or a custom job with the network or station's name -- is etched on a metal plate inside the tube. An electron beam generates the image electronically, which is always the same.
So it's whimsical that Don Knotts or anyone could stand IN FRONT of the test pattern image, so he is front of a printed version in this movie. And since his
head would be blocking the image of the Indian, and the Indian is what people remember from the days before 24-hour broadcasting, it was moved to a corner.
Photo of a monoscope tube without image of the Indian, which seemed to be an American thing.