I had no problem with The Fall. It bent around the core and went mostly through the mantle...
Except it is specifically said that it goes through the core and the mantle itself is still a non-solid, very hot, area that'd have an object experience tremendous pressures.
I won't disagree with the heat and pressures, but the diagrams I saw on the screens showed a distinct curve.
The curve would be from having to link up wherever The Colony is in Australia with the UFB capital in London. The
antipodal point of any city in Australia would be in the North Atlantic to the south and west of Britain.
So there was a curve in the tunnel, but dialogue, graphical displays, and events within the film made it clear that they went through the core itself as well. In order for them to experience neutral gravity (not a lack of gravity but gravity cancelling itself out by pulling you in all directions at the same time) they would have to be in the core. In reality Earth's surface isn't uniform, and the core is wobbling around a bit, so there's no fixed point where this would happen, but when you're dealing with something as ridiculous as The Fall already that's a minor point. It was cool to see the free floating part included, at least.
Besides the problems of heat, pressure, and elasticity that would make building such a tunnel impossible (
the deepest we've ever gone barely scratched the surface), the characters actually left the building-sized "train car" within the tunnel just after passing the core, which was just taking something stupid and multiplying it by eleventy.
In order to cover 8,000 miles in 17 minutes, the car would have to travel at 28,235 mph through a tunnel that was somehow pressurized and had breathable atmosphere all the way through. In actuality, because of the curve it would be more than 8,000 miles, and because the car would need to accelerate and slow down, it would have to be significantly faster than that in the middle section of the trip. So, we have people running around on the surface of a train car moving at Mach 37 just after passing through a solid metal core about as hot as the surface of the Sun (roughly 9,800 °F) with roughly 3,600,000 times the mean atmospheric pressure at sea level.
I appreciate them making an attempt to insert a fairly unique and far out scifi concept into the film, but it was pretty regoddamdiculous. It was a neat visual having a building-sized elevator moving through a tunnel, though.
As far as the movie itself, I think I would have judged it better had it ditched the name recognition with the PKD short story and the 1990 Arnie film, and just made it a straight futuristic spy movie without the memory implant story. While doing that likely brings in more money, it also invites comparison to the earlier movie, which this film unfortunately falls short of overall despite being better in some respects.
I actually think the action scenes in this film are more creative, better choreographed, and more visually interesting than the 1990 film, without Verheoven's fun but way over-the-top gore. The first fight between Beckinsale and Ferrel was great and brutal, the futuristic fevela chase was fun with the addition of sudden drops through the floor of the buildings, the hovercar chase was awesome, the 3d elevator chase with cars weaving in an out everywhere was exciting, and the zero grav fight using guns to propel themselves around the room was cool. As I said, I liked The Fall as an idea and setting for a battle, but I wish they had made it move through a vacuum tube in the crust and take a couple hours to reach its destination at least. They could have fought with lightweight environment suits on.
Apart from The Fall, the technology in this movie was pretty neat. I thought the hand phones, hovercars, genetic engineering, police/combat robots, aircraft, personal holograms, and tech-laced armor and guns were pretty realistic developments for 70 years from now. Even the memory implants are believable. The multi-layered cities of The Colony and London were visually arresting yet believable outgrowths of over-population because everyone is crowded into the two safe zones, presumably because they erected some sort of electromagnetic field or barrier to repel the chemicals which for some reason never dissipate or move and are heavier than air and stay near the ground.
The call-outs to the original were fun, especially the three-boobed girl and the lady at the security checkpoint who looked like Arnie's disguise.
Colin Ferrel is a better actor than Arnold, but he lacks the screen presence and ability to deliver a good quip as he dispatches a bad guy. As much as I like Jessica Biel, personality-wise her character doesn't compare to Rachel Ticotin's Melina. I think Kate Beckinsale was about the equivalent of Sharon Stone, however. Bryan Cranston was criminally underused, however, and not given enough scenery to chew like Ronny Cox in the original. Plus, it made no sense whatsoever to have the Chancellor of the only actual country left on Earth to lead the troops into battle or walk into the terrorist HQ.
Overall, it wasn't bad, but it pales in comparison to the original, the action sequences, while cool, were nonstop and plot/character development were sacrificed as a result, and the script leaves much to be desired. I'd give it a "B-."