Call it Fate...
The first time I saw Ghostbusters, the way Murray delivers that line (Call it Fate, call it Karma, call it Destiny...) and the way they've got the music stirring in the background, I thought that he was going to bust out into a musical number. For two seconds, I thought this movie was a musical and I never knew that.
Were they trying for that? Maybe. I don't know. But it kinda cracks me up that there's this false-start musical number that never existed.