Cranston, Farrell and Nighy notwithstanding, this sounds to stupid to pay movie price for. Waiting for the DVD.
Actually, other than that one transportation device, the movie is about 100x more likely than the original. After all, which is more likely - humans build a device that travels through the Earth, or radiation on Mars turns humans into a variety of mutants, and aliens build a machine that creates a breathable atmosphere on a planet with a fraction of Earth's gravity. Not to mention action scenes that wouldn't work with Mars level of gravity.
I'm assuming the tunnel was created before human civilization fell, so to speak. But then, assuming this is the case, it is quite a coincidence that the only two habitable areas on the Earth are connected by the thing.
Someone made a comment that this one follows the short story more than the original. I don't know if I agree. Yes, the story didn't have Quaid (actually Quail in the story, but understandably changed considering who the VP was at the time) go to Mars, but he did go there before his Rekal trip.
Synopsis for the story - so spoilers!
Quail is a lowly salaried worker in a future Chicago. The story never says he is some kind of clerk, I believe, but does not introduces any characters from work. He dreams of eventually going to Mars, and on a whim goes to Rekal for a spy adventure on Mars. Before the procedure is performed, Quail remembers actually being on Mars as a secret agent, and accuses the people at Rekal of blowing his cover and bringing back his buried memories. He doesn't kill everybody, though. Instead he goes back to his apartment and finds further evidence of his trip to Mars, like alien worms he brought back and hid away.
At his apartment he tries convincing his wife he has been to Mars, but she doesn't believe him. He is confronted by the government police, who explain that he is really a secret agent who went to Mars to assassinate a political leader and had his memories erased to cover up the incident. His desire to go to Mars and be a secret agent indicates that the memories cannot be entirely erased, and thus the police see no other option than to eliminate Quail. He also had an implant in his brain that allows the government to read his thoughts. Quail jumps the policeman and disarms them - the only real action scene in the story - and flees his apartment.
Once free, he discovers the government can communicate with him telepathically. Quail makes a deal with the police that he will turn himself in if they can replace his memories again, and this time a stronger fantasy be implanted in his mind. The government psychologists analyze Quail and discover a childhood fantasy of him foiling an alien invasion where the aliens agree to never return as long as Quail is alive. They plan to use this as the basis for the new implant when they again discover that the alien invasion is not merely a fantasy, but an actual memory. They let Quail go, realizing that by killing him they only invite the aliens to return and invade Earth.
As you can see, other than the very basic story points, neither movie really follows the short story.