 ::::Whilst I agree with your comment, is this not original research? One has to assume Lucas knows about film-making and what the names are for things involved in film-making. It's not a slip of the tongue  he say's R2D2 is a MacGuffin, and then explains that in the industry that means something that everyone wants, and so causes the characters to do certain things. That it might not be the a MacGuffin sensu strictu per Hitchcock, then perhaps sensu lato R2D2 is a MacGuffin in the sense that at least some movie professionals mean it. Cheers, Neale  