When Chin Ho and Fred Grayson accept the package of glucagon at the airport, Chin sits in the rear right seat while Grayson sits behind the driver. On arrival at the hospital, Grayson gets out of the rear right seat while Chin gets out of the left rear seat.
Near the end when McGarrett and Danno are following the blue pickup Danno's suit alternates between brown and green and McGarrett's tie alternates between blue and red.
At the moment that the sheet is pulled over Mrs. Grayson's face to indicate that she has died, a poorly-timed closeup shows her eyelids still visibly fluttering.
When the plane lands at Tokyo, they're all American made cars on the tarmac. No Japanese cars can be seen.
There were actually 2 different helicopters used in the air search scene. First was a Hughes/MD 369 also known as the Hughes 500 and shortly later it magically turns into a Bell 206 JetRanger.