The kidnappers attempt to flee from McGarrett in a private plane. When they board the plane and McGarrett chases them around on the taxiways, the plane is a twin engine propeller aircraft. When it becomes airborne, the plane is a twin engine jet.
When Steve McGarrett and Danny Williams drive away from the location where the ransom money is delivered, McGarrett's car clearly has a rear view mirror. The mirror is missing for the rest of the story.
When Danny radios to Steve that he is stuck in traffic, he's driving Steve's old 1968 Mercury. When Danny reaches his destination, he's driving a 1975 Ford.
The board in McGarrett's office has a detailed map of the Honolulu area. With the shed at the center, he draws a circle with an eight mile demarcation. But he ends up with a circle that seems to have a radius of a mile or so at best. Realistically, an eight mile radius circle would likely encompass a third of Oahu.
The technology of the Coast Guard cutter enabled it to track Colburn as he swam underwater to the ransom drop-off point. But after he was shot by Asuko upon returning to the boat, it was not reported to McGarrett that he was still in the water.