If Marlene weren't in the same studio as NG's show, she may not have seen a picture of the bag.
A lot of times, those types of interviews are done with the remote subject sitting in a small room with a camera directly in front of them. They can hear the voice of the interviewer (in this case, NG) through a speaker located directly below or above the camera, to encourage the subject to look towards the camera.
There often isn't a screen, so the subject can't see the face of the interviewer or whatever is being shown by the producers in the background. In fact, at the time of the interview, the show may not have located the picture that they used. TV often tapes disparate elements and then collages them together.
It's a step up from a telephone interview but still not like being in the studio with the interviewer.
IF Marlene watched the show as it aired (many people don't because they cringe at the thought of seeing themselves on TV) and called the NG show to correct the detail, they might publish a correction... or they might not.
Depends on the individual show, the producer or main talent's dedication to truth and detail, the judgment on how important the error is, whether they have enough time on a subsequent show to run the correction, etc.
