u/mflem920

This isn't "Why didn't they just use the gas from the DeLorean that Doc stored in the cave?"

That IS a good one though. Doc would have drained the fluids for long-term storage and would have kept them just in case he needed them. Properly stored, gasoline can still be effective for 1-2 years. (The 3-6 month period is when it STARTS to degrade, not when its unusable for combustion).

But this isn't that plot hole...it can be explained away too simply by "Doc didn't keep the gas" or "He used it in another experiment before Marty got there, maybe to build that big ice machine".

No, THIS is the BIGGER plot hole of: Doc is in 1885. The first US Petroleum refinery opened in 1850. They mostly refined a byproduct of salt mines called "rock oil" into Kerosene or other heating/light oils, but cracking it all the way to Gasoline was well within their capabilities. They just didn't have a use for it so they usually just burned it off as a waste byproduct.

By the 1880s there were several commercial refineries like this, some operating in Southern California. Most owned by Standard Oil and John D. Rockefeller.

Gasoline of an appropriate grade and octane was WIDELY available for the pair to acquire in 1885. The invention of the gasoline-powered engine patented in 1864 is proof of this.

Doc is technically correct "There won't be a service station around here for a very long time", but that doesn't follow that gasoline didn't exist. They just had to go to San Francisco to get it. Acquiring a quantity for "scientific experiment" would have been a simple matter and an already established process since there would have been commercially available gasoline engines since 1872 and they needed fuel. It also would have gotten both of them out of town for each of their respective Buford Tannen predestination events.

OK, this is certainly a bit late, and it's already punching down on a thoroughly bad movie.

But...I just saw the movie involuntarily, so.

The movie opens and the first thing we see on the screen is "Earth - Cenozoic Era"

And I know they mean to say "a really really long prehistoric time ago".

But we're IN the Cenozoic era TODAY. It ranges from the Cretaceous–Paleogene extinction event approximately 66 million years ago to today.

So the placard is a little vague to establish a timeline. Do they mean 50 million years ago? Do they mean during Ming Dynasty China? Do they mean least week? ALL of these periods are contained within the Cenozoic Era.

Geological eras are a good way to give a time reference when something happened so long ago that a hundred million years here or there doesn't matter. Which I'm sure is what they were going for. But then they picked the ONLY era where things have happened in it so recently that that timescale is meaningless.