After McGarrett leaves the gambling raid, his car is a 2 door. While driving to the dock, it becomes a 4 door.
The smuggler agrees to take $37.25 per ounce for the gold. That means one-million dollars of gold would weigh 1,678 pounds. which by estimating the size of the ingots would require close to 400 ingots.
When McGarrett has cars 9, 12 and 6 check in on their car radios, the cop in car 6 answers and is holding the mic backwards. He notices it after speaking and turns it around just before the scene changes.