It doesn’t really bother me because the movie is so damn fun otherwise, Buford is both a hoot and absolutely more sinister than Biff (or Griff) ever was, the score is great, and the finale is spectacular (again, minus Doc showing up with his gremlin children in the flying train). But I do like bringing it up, it makes for fun conversation. As for the whole “paradox” thing, I feel like the only thing that would change is that 1955 Doc would have to replace whatever they took from the 1885 Delorean. I do think I remember the line about the gas being filled though, and it certainly is possible that Doc drained the gas either getting himself to 1885 Hill Valley or storing the car.
Dang, now I’m in the mood to watch these again.