Continuity mistake: At the end of the movie, when Neville is behind the glass and he is thinking and all the sound goes away, you can see the bite mark that the zombie gave him. While the shot is changing between him and the zombie, you can see the bite mark change sides of his shirt.





Answer: In the alternative ending Dr.Neville, Anna and Ethan are seen driving a car over a bridge that wasn't destroyed. The army would need to leave a entry/exit point, but it would have been heavily guarded until everyone died.