Other mistake: After Zak and Francesca get through the giant fan, Zak unscrews the vent cover and it drops like a rock, but as the camera pans out you can see that everyone is still frozen. So, wouldn't that mean that the cover is supposed to look like it dangles in mid-air and be in normal time?
Other mistake: When the young couple goes into town everything is moving very slow, almost as if they are frozen. When they are looking at the Mustang, look in the background. The guy standing still has become a victim of wind. Notice his shirt flapping in "real time" and not "hyper time". If everything is slow then how come the guy's shirt is blowing in the wind?
Other mistake: When Zak is trying to sell his father on co-signing for the '65 Mustang, he talks about putting a V8 in it. As evidenced by both the first look at the Mustang's V8 emblem on the used car lot, and the last look when he revs the motor at the end of the movie, the Mustang already possesses a V8.