“While almost all of the dialogue in original [Ghostbusters] screenplay is echoed on screen, the Venkman character is completely improvised. It’s as if Bill Murray was given a mumblecore-style essay about each scene and then permitted to say whatever he wanted as long as he got the point across… He’s like a jazz musician who knows, ‘I have eight measures here and have to hit this note here and as long as I follow those rules everything else is up to me.’â€
- Writer/director Jason Reitman to EW about the improvisation skills of Bill Murray in his dad Ivan’s movie Ghostbusters.