Character mistake: When they exit the bowling alley with the dog, the dog is never put in the car, only the cage.
Character mistake: Near the end, just before Derek and Danny depart at Danny's high school, Derek says to his brother "I saw a car cruising by the house last night when I pulled out of there with Seth." The car that was shown driving by their house the previous night was in a brief scene right after Derek and Danny took down all of their nazi posters, and before Derek took a shower. He had not just 'pulled out of there with Seth.' The last time he had seen Seth at this point in the movie was at Cameron's party where Seth had almost shot him.
Suggested correction: Just because Derek says to Danny that he saw a car driving by their house when he left with Seth and a black car drove by later in the movie doesn't mean that this is the car Derek was referring to. There are many possibilities to explain what Derek was referring to (perhaps he was paranoid and saw an ordinary car driving by that he thought was scoping their apartment out) but it doesn't mean that the black car is the one he was referring to when he warned Danny.
Character mistake: After the first attempt by the kidnappers to get the ransom money, they tell the FBI to bring the money behind the Foo Chow restaurant. Clive gives Carter and Lee the exact same destination. Why in the world would kidnappers give the FBI a drop-off location exactly where they are based?
Character mistake: Jack accuses Marion of being a mug punter because she bets on the lottery, despite the odds of winning of "14.5 million to 1." The odds of winning the lottery are in fact 13,992,000 to 1 - not much better, but at least a precise figure.
Character mistake: Just after the shootout between the robbers and the armored truck drivers at the dip in the road, the teacher that is with the robbers pumps the shotgun about 3 times, without firing a shot after they crossed the water. This would just waste a perfectly good cartridge, since they hadn't been shot yet.
Character mistake: At the meeting in Washington the general says nothing more frightening than a soldier with his M16A1, but they were using M16A2s.
Character mistake: The banner of the fundraiser event for the Gotham upper class says "Childrens Hospital", no apostrophe. (00:11:55)