Revealing mistake: When Julie is talking to Stuart about her future, snow is falling in front of her. We can also see the wind is blowing, as it moves her hair. The snow, obviously CGI, is still falling straight down, and doesn't interact when the wind blows.
Continuity mistake: When Julie and Stuart have breakfast at the Waffle House, the position of the fork in her hand is inconsistent between shots, and so is whether it has food on it or not. (00:14:40)
Other mistake: There is a car chase between a station wagon and a sports car. The sports car hits the rear of the station wagon, hard, but neither car is damaged.
