Kevin sent me the below and insisted that I post it right away...apparently he was slow at work and thought that writing a blog post would be the best way to occupy his time. So I present to you, without further ado, Kevin's return to the blogging world (finally!).
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Leslie often pokes fun at the random nature with which my brain operates. My thought trains are generally sporadic and discombobulated, with inexplicable leaps between topics. Even I don’t know where my ideas come from—all I know is that they’re golden.
Recently, as I was awaking from a night’s sleep with my eyes still closed and my brain still fuzzy, I was overwhelmed by a sudden and deeply profound realization: There is a major plot hole in Back to the Future III. I must admit, I have not consciously thought about or watched the Back to the Future franchise in years. But as I stumbled to the bathroom and wiped sleepy bugs from my eyes, I knew that this inspired revelation must be shared with the world.
For those of you who, like me, have not watched Back to the Future III in a while, I’ll provide a brief recap: The movie begins with Marty standing next to a tunnel in 1955, burning the Sports Almanac while Doc flies overhead in the DeLorean during a lightning storm. Doc (inside the DeLorean) gets struck by lightning, which causes him to be sent back to 1885. Moments later, a car rolls up and delivers a telegram, which Doc sent to Marty from 1885 telling him he’s fine, but the lightning shorted the circuits on the DeLorean and Doc can no longer travel through time. However, he tells Marty that he hid the DeLorean in an old mine shaft so that Marty, along with the 1955 version of Doc, can fix it using parts that exist in 1955 (but not 1885), to return Marty back to his home time of 1985.

In the interest of brevity, Marty and 1955-Doc decide that Marty has to go back to 1885 to rescue Doc, so they take the DeLorean from the mine shaft (which Doc left there in 1885) and head back to 1885. Upon arrival in 1885, Marty is attacked by Indians and the DeLorean’s gas tank/fuel line is punctured, spilling all the gas. Marty is initially unconcerned, but Doc informs Marty that even though Mr. Fusion powers the circuits and flux capacitor, the engine relies on regular gasoline, which Doc informs him will not be available until sometime in the next century (meaning 1900-ish). Hilarity ensues as Marty and Doc have to find an alternative power source to get the DeLorean up to the requisite 88 mph in order to get back to 1985 (spoiler alert: they use a train, after horses fail).

So as you can see, the entire conflict in the movie centers on a way to get the DeLorean up to 88 mph, which they could admittedly do if they had gasoline (there’s even a scene where they try substituting hard liquor for gasoline—it doesn’t work).
I realize that was long, but for those of you still with me on this journey, the vistas are about to become delightful.
Here’s the plot hole: They do have another source of gasoline! Remember that Marty is driving the DeLorean that he found in the abandoned mine in 1955. But that DeLorean was placed in the mine (for Marty to find) by Doc in 1885. Because Marty brought the 1955 DeLorean back in time, the DeLorean that Doc put into the cave (only days before Marty’s arrival in 1885) is still sitting in the abandoned mine and has gasoline in the tank. In other words, there are two versions of the DeLorean currently sitting in 1885. One has a hole in it (1955 version) and one does not (1885 version).
The idea of having two of the same thing at the same time is played on throughout Back to the Future II, but seems to have been forgotten in Back to the Future III. I find it cruelly ironic that throughout the series, Doc chastises Marty for “not thinking fourth-dimensionally,” but fails to heed his own advice during such a crucial hour.
There you go! This movie came out in 1990, so it only took my razor-sharp mind 21+ years to figure this out. For those of you who figured this out earlier, like when you first watched the movie, congratulations! Your intelligence is obviously unparalleled, but it's a shame your childhood was cut short and you had to learn prematurely that Hollywood is not always perfect.