When the new president talks to the world on shortwave radio, some kids are adjusting a TV antenna in one shot. Shortwave radios wouldn't work with TV antennas, they use two significantly different frequencies. Shortwave is a much longer wavelength and would require larger antennas to work.
Brent Spiner performed the majority of his scenes alone, with no other principal actors on the set. In fact, Spiner is digitally inserted into some scenes where he appears with other principal actors.