Visible crew/equipment: In the scene where the bus jumps the gap in the freeway, as the bus lands, the interior camera jerks down and we clearly see the cameraman's brown shoes.
Visible crew/equipment: When Sam is shot in the shoulder it shows a camera shot from the side of the bus going into a wall. In this camera shot you can see the shadow of the camera. (00:40:15)
Visible crew/equipment: A film truck with its crew and equipment is briefly visible in the reflection of a red van four shots after Jack directs Annie onto the shoulder (use pause to get a better look). (00:46:15)
Visible crew/equipment: After the bus exits the freeway, as it drives on the city's streets the forward looking street-level action camera is visible, mounted behind the tire. (00:49:05)
Visible crew/equipment: During the passenger transfers at LAX, a cameraman is visible through the bus doorway two shots before Annie glances over her right shoulder twice. (01:27:35)
Visible crew/equipment: When McMahon is giving Jack directions to the vacant 105 freeway, a well-dressed crew member wearing sunglasses and a big grin is visible sitting in the aisle of the bus. (00:49:50)
Visible crew/equipment: Right after the bus passes 50 mph and arms the bomb, filming equipment can be seen in the Jaguar's vent window reflection. (00:36:45)
Visible crew/equipment: When the credits are rolling, a crew member in a gray shirt on the lower left portion of the screen can be seen waving extras into the street. (01:51:05)
Visible crew/equipment: After Tuneman's Jaguar hits the water barrels, a film crew's truck can be seen out the bus's rear window just before the shot cuts away. (00:40:05)
Visible crew/equipment: When Harry's colleague hands him a printout of Howard Payne's newspaper article, a boom mic reflection is visible on the window right above the bomb schematic diagram. (01:15:15)
Visible crew/equipment: When Jack runs with the car after the bus just before yelling to the driver that there's a bomb aboard, when he does a risky maneuver, a cameraman and another crew member sitting on a tracking vehicle are briefly visible on the right side of the screen. (00:36:20)
Visible crew/equipment: When the guard walks past the pillars at the start, on the first pillar you can see a shadow made by the film crew. (00:03:00)
Visible crew/equipment: As Jack inspects the bus's speedometer for signs of tampering, a camera can be seen in a reflection on the window to Annie's left. (00:44:35)
Visible crew/equipment: As Harry walks out of the office after telling his colleagues to search for their mystery bomber via pension fund files, a boom mic pole is reflected in the left window when he says, "I've seen this a**hole." (00:55:25)
Visible crew/equipment: When Jack's Bronco weaves across two lanes of traffic on the highway seconds before throwing it in park to catch up with the bus on foot, a camera can be seen, mounted in the Bronco's back seat. (00:34:15)
Visible crew/equipment: A film truck is reflected in the bus's bumper when Jack exits and steps onto the Suburban. (01:11:15)
Visible crew/equipment: When Jack flashes his badge at Tuneman, a camera's shadow is visible on the pavement. (00:35:00)
Visible crew/equipment: When the bus is traveling on the shoulder, a camera truck is visible to the extreme left immediately before Annie asks whether or not she should stay on the highway. (00:46:35)
Visible crew/equipment: After Keanu steals Tuneman's car there is an overhead shot from a helicopter as he's trying to catch up. The shadow cast by the helicopter is visible at the beginning of this shot.
Visible crew/equipment: As the bus goes down the freeway, there's a shot of the police chopper following the chase. The movie camera chopper is seen above and to the right of the police chopper that is referred to as a news chopper, but isn't seen again.
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.