I don't feel this is true at all. I think people start to question reality when the plot is weak or when the object that in unrealistic is tied to the plot in a

I don't feel this is true at all. I think people start to question reality when the plot is weak or when the object that in unrealistic is tied to the plot in a significant way. I've never sat through Back to the Future and seen a nerd say "but what exactly does a flux capacitor do in order to enable time travel, this movie is so unrealistic!". I think that as long as a minimal effort is given to explain away these points it is satisfactory to most people as long as those points are not essential to the movie: the physics of time travel is not essential to the story of Back to the Future. However, the more important to the movie, the more time must be spent. Cloning dinosaurs, and specifically how they clone dinosaurs, was pretty important to Jurassic Park. Hence, more effort was placed in explaining this to the audience (they're all girl dinosaurs, fossilized dna, need frog dna, etc etc). This is significantly more involved than "oh we have a flux capacitor for that" explanation. Both are perfectly fine though, since they match their necessity to the movie. I personally felt that Avatar succeeded at this level of explanation. Aside from "unobtanium" somehow making it past the first edit of the script, the technological/biological stuff was fine: Unoriginal? Yes. Uncomfortably unrealistic? No. However, I think absolutely everything else about that movie was pretty subpar. The plot was really uninspired. Its sad, so much gloss on top of such an empty story. On top of that, I really was not that impressed with the graphics. I'm sure plenty of people will tell me I don't know what I'm talking about, but when I'm 70 years old and someone asks me, visual effects-wise, what was the highlight of my movie going career, I'm going to say seeing the brachiosaur in Jurassic Park, and probably won't even remember Avatar.