For those of you into Classic Mel Brooks films, he plays on this in "High Anxiety." The ,movie was a spoof on Hitchcock in general, but the event that gets the plot rolling is that the main character, who is afraid of heights, as asked for a room at a hotel that is to be no higher than the third floor. When he gets to the hotel, he finds that he has been booked on something like the 18th floor. He starts to complain, and the desk clerk tells him that they had his reservation for the 3rd floor, but a Mr. Maguffin called and changed it to the 18th.
My understanding was the Maguffin was the term Hitchcock used to refer to the "inciting incident" of the movie, or the event which really gets the plot going.