Of course, using six digits as standard would make it impossible for a TV viewer to decipher the number and dial it. TV and movies could get in trouble if the owner of a number gets harassed because his number was used in a fictional setting.
Not necessarily. Six-digit phone numbers were in use in the United States into the 1960s, although I can't find a source that says clearly when they were discontinued.
Likely enough the TV show skipped a digit because how many hours of boring screen time have rotary phones added to movies and TV shows? And after a couple digits are dialed who's even counting?