In the final scene while McGarett is at the Honolulu Airport, a US Air Force F-100 Super Sabre jet can be seen taking off in the background from right to left. Honolulu shared runways with Hickam Air Force Base.
When McGarrett was in the Navy, he met Cathy who dated him quite amorously only to leave him to marry her fiance in San Francisco. In this show, Cathy was strongly suspected of murdering her husband. Citing the accumulation of evidence against her, Danno informed him that she should be arrested, but he refuses to do so. Further, when Danno suggested that Steve withdraw from the case on the basis of his personal involvement, he also refused. In real police work, an officer with such a conflict of interest would have been removed from the case.