At the end of the movie, when they are cooking burgers, they flip half cooked burgers, put cheese on them, and as the camera is panning away, they are flipping the burgers. Nobody flips burgers once the cheese is on them.
When Kevin makes the large McDonald's order and realizes he doesn't have enough money, he changes his order to a Quarter Pounder, fries and Coke, however when he walks out of the McDonald's, he only has the bag with the hamburger and fries...no Coke.
The mobsters' Lincoln Town Car changes at one point during an aerial shot in the movie. During the shot, you see the rear end belongs to a 1981-1984 model Town Car, while during the rest of the movie the rear end belongs to a 1987-1988 model.
When Kevin is chased by the bad guys, he is carrying a McDonald's paper bag, which gets crumpled and creased during the journey. But once Kevin gets into Gary's car and throws the bag down, it is creaseless.
When Kevin and Steve are standing on the railroad tracks, the train is shown approaching much faster that reality. Numerous times the train is seen approaching in the distance, then is further back, then is closer again.