The magnetic collars in the movie can't possibly work the way they are shown. First of all, the magnetic collars don't start attracting West and Gordon until they hit one and "reverse the polarity." Reversing the polarity means they should have been _repelling_ each other just as strongly in the first place. Also, if they were strong enough to drag Gordon hundreds of feet through the desert to the rail tracks, he and West could never have separated themselves. And finally, magnets could never make metallic flying discs move anywhere in the fashion shown without them running out of inertia.