At the beginning credits Shockley gets into his car and drives off past a Penney's department store. He then gets on a freeway and drives around town. After he stops and breaks the bottle of whiskey, you can see the same Penney' store behind him.
In the constable's car, there is a can of Tab sitting on the dash with the bar code side visible in all the head on shots. After Shockley and the constable return to the car from making the phone call the can of Tab is turned around to the front; easy to tell because the bar code box is missing and the Tab lettering is larger.
Upon learning that Shockley has hijacked a bus in Wickenburg Arizona and is en route, Blakelock announces that it will be three hours before the bus arrives in Phoenix, 150 miles away. Actually, the two cities are only about 50 miles apart - a distance that can easily be traveled in an hour or so.
Even though the route Shockley and Gus was supposedly cleared of all traffic and pedestrians, people can be seen in parking lots along the route and vehicles can be seen crossing intersections just behind them.
In the big final scene, there is no way that police could line up on both sides of the street, and finally surround the bus, and fire over 8,000 shots at the bus and have no stray bullets hit one of the officers.