Revealing mistake: When Payne opens the money bag in the overhead shot looking down into the bag, as the dye bomb explodes, Payne is wearing a transparent protective face shield, that is partially visible at the top left corner of the screen. Payne is not wearing a face shield in the previous or following consecutive shots. (01:42:35)
Visible crew/equipment: When the police officers on the LAX vehicle are attempting to rescue all the passengers by driving up beside the bus, there's a camera angle between the bus and LAX vehicle, as the people are jumping out of the bus onto the LAX vehicle. If you look closely, you can see camera crew reflections on the rear bus fender, and also a man sitting wearing a white shirt with sunglasses reflected in the window of the open LAX vehicle door.
Visible crew/equipment: When Jack is trying to pry open the subway train's doors, a boom mic can be seen mounted on the car's interior, suspended from the ceiling. (01:40:30)
Visible crew/equipment: When the speeding bus takes the really sharp right curve, while it leans over on its left wheels, you can see the crew's tire rig lift under the bus that they used to keep it steady for this stunt. (00:50:10)
Visible crew/equipment: When Jack is talking to Howard Payne from the payphone, you can see the boom microphone's reflection on the phone receiver in several shots. (00:30:00)
Answer: If they had, there might have been the possibility that to get to these routes they would have to go down a different road and depending on which route they take they might have to slow down to make the turn which would likely cause the bus to drop below 50 mph. Better to just keep going straight and keep the bus going. There's also the possibility that had they taken a different route, they would have to deal with a lot of traffic especially if there was traffic stopped at a red light. By using the highway, there'd be no traffic lights and less traffic to deal with.