When Nesbit in the sedan is chasing Matt in the underpass, you can see the right headlight of Matt's truck is off, when they get to the next shot the light is on.
While none of the witnesses came forward, there was an abundance of physical evidence at the arson scene. As an example, the fire truck was used to ram vehicles out of the way, and Casey used a pickup to ram other vehicles to clear the road. This would have caused damage that would allow an investigator to match the damage, such as paint transfer, to the vehicles. This in turn would support the firefighters version of the events.
When the hoodlums attempt to overrun Chief Bowden at the armored car wreck, there are bars of gold that were tossed to the pavement and some scattered. As the police take the perpetrators into custody and walk away someone kicks a bar of "gold". It slides away easily with a ceramic sound. Gold bars would not do that.