I believe that, if these "mistakes" aren't intentional, they are at least a demonstration of the lack of respect or care that they have for the President and those people who voted for him.
If the mic had been on for ten or fifteen seconds, I might accept that it was a "glitch." But they left the mic open for a minute and a half, and we're supposed to believe that no one in the control room caught what was happening? Riiiight.