The latest word in unnecessary threequels: Bill Murray’s refusal to make Ghostbusters 3 will not stop Dan Aykroyd, who says he’ll just re-cast the part of Peter Venkman. The weirdest thing about this is that Aykroyd assures audiences that Rick Moranis will be involved in the third movie, because “None of us would want to do the movie without having him as a participant.†Why he doesn’t feel that way about Bill Murray, whose role in the original film was about twelvety billion times more important than Moranis’, is a mystery the likes of which no one has seen since the outbreak of unexplained paranormal activity in 1980s New York City.