Apparently, the term kinda comes from golf, where it's a synonym for a "mulligan."
Most of us understand life as not having any do-over's. (It's significant that in golf such do-over's are not part of the official rules.)
You can't go back. Some opportunities only come around once. Time only flows in one direction. There are all kinds of ways of expressing this thought.
Yet it's surprising how many movies have do-over's.
- Vertigo is a kind of a negative do-over, or a do-over with a bad outcome.
- In Million Dollar Baby, the trainer gets to accept his loss of his daughter by accepting the loss of his surrogate daughter.
- After not doing anything about Darth Vader and seeing Darth kill his mentor, Luke gets a chance to destroy Vader and all his henchmen.
- Groundhog Day is all about do-over's: the guy's whole life becomes nothing but a do-over.
I'm sure examples could be multiplied.
I have observed elswhere that the third act of a Hollywood movie is usually, strictly speaking and in the logic of whatever film it is, impossible.
- Wall-E gets his memory erased--yet magically he still remembers Eve.
- The Blade Runner could easily be killed by the powerful robot, but the robot relents, because he has become human in the end.
- Rick gets a chance to get Ilsa back and yet accepts willingly that life is a place in which he and Ilsa cannot be together.
- A Saint Louis family that must move to New York City in the era of the Saint Louis World's Fair discovers that this decision was not so irrevocable as all that.
- In Hidden Fortress, one general suddenly has a change of heart and releases his prisoners.
Most people would interpret these as lapses, failures in logic, a weakness in writing.
I don't believe this is the case.
Instead, I believe this sudden shift is a useful, almost necessary, and altogether pleasing part of the feature film structure.
First, you don't want the audience to know everything about the ending. You want some element of surprise--and audiences want this too.
Hence a problem for screenwriters is: be logical and make sense, but surprise them at the same time. The movie's ending must be inevitable and yet surprising. Talk about an impossible task.
But this is in a sense the audience's demand. The audience makes conflicting demands on the filmmakers. But--hey!--almost all of life involves conflicting demands. Life isn't "logical" in the sense of being devoid of contradiction and conflict. Life is full of conflict, and the more dramatic and messier it is, the more interesting.
So the screenwriter must fulfill contradictory demands.
I've written elsewhere about how the audience usually must be lead to the wrong expectation, so that the ending can be a surprise.
So a changeof heart or character or reality near a film's end is very useful.
Second, we all feel conflicted about reality. We have a sense 'this is what reality is.' But we're not entirely happy about it. We know that dreams don't often come true--if ever. But at some place inside ourselves, we still want it to be so. We don't want reality to win. We want wishes to win.
This is the origin of the audience's contradictory demands upon the filmmaker: be logical and realistic, yet make me happy at the same time.
Movies can either let reality win and disappoint us.
Or movies can let wishes win--and we will know they are false and fail to be affected powerfully by them.
If, however, a movie first lets reality win and then lets wishes win, the movie has things both ways. The taste is bittersweet.
The inverse would be: let fantasy win, then destroy fantasy--too heartbreaking to contemplate, too real. That's not a movie: it's a bill coming due.
With the double ending, we are very pleased, because our sense of reality is satisfied, and our wishes are gratified, too. Contradictory demands have been met.
That's why this kind of aspect of the third act of a feature film is almost necessary--just not entirely so.
--E. R. O'Neill