As the VW bus is being lifted from the river, Briscoe says, "Maybe we should try to start it." That would not be possible, as the VW is clearly missing its engine, which would also make it impossible for the victim to have driven it into the river.
In the opening scene as the VW Type II bus was being pulled out of the water it was quoted as circa 1968. The split windshield was last made for the1967 model. From 1968 on it was a single windshield.
When searching through a box of things, Rey Curtis (Benjamin Bratt ) mentions seeing a "Dr. Pepper's Lonely Hearts Club Band" tape. It actually was, of course, "Sgt." Pepper's.
The premise of the opening scene is that the divers are looking for a handgun thrown into the river minutes or hours earlier. There would be no need for a crane capable of lifting a vehicle to be at the scene.