Continuity mistake: Frank and Jack arrive at Audrey's house and Lola enters the Audi. She opens the window and uses her guns. In the following shots the window is sometimes open, sometimes closed.
Continuity mistake: In the plane fight scene before splashdown, the plane was falling and turning/tilting as shown from the outside, but when the scene changes to the inside the fighters are standing straight.
Continuity mistake: Some guy puts a bomb under Franks car because they managed to escape, yet when he escapes from the cops (with Lola in the car), the bomb isn't there. A while later when the kid has been dragged out of the car, he looks under it, and sees the bomb's reflection in the floor.
Continuity mistake: When Frank is arriving at the school to pick up Jack at the beginning of the movie it shows him pulling up to the school and there are no other cars parked on that side of the street. When it cuts to show him sitting in the car waiting, there is a car parked behind him. When it cuts to outside again, there is no car behind him.
Continuity mistake: In the car chase after the doctor's, the bomb on the bottom of the car stands out while Frank drives away, but in the chase where you get a lot of low angles the bomb is very obviously gone. Then it appears again when leaving the boat yard / docks ready for the crane scene.
Continuity mistake: During the escape from the police the Audi's headlights switch between being on and off repeatedly.
Answer: The police will just get in the way and slow things down too much. Frank can operate outside of the law and get more done and get it done quicker. Plus, they can't just take Audrey's word for it.
TedStixon