When intelligence chief Brent bends over the man McGarret shot, he immediately removes the knife from the man's hand. The scene shifts to McGarret on the phone, then back to Brent, who is shown removing the knife from the dead man's hand again.
On the way to the drowning victim McGarrett leaves 5-0 HQ in a 4-door and arrives in a 2-door.
Danny states that the "S.S." in "S.S. Arcturus" stands for "Steam Ship". It actually stands for "Screw Ship" - as in the ship uses a propellor rather than sail or paddlewheels.
When McGarrett is being followed by the same sedan, he calls for a HPD ambush on the police radio, but he never takes his thumb off the talk button, even when dispatch is replying. Since radios are one way devices, it is necessary to release the talk button in order to hear the other party.
When McGarrett is being followed by the Intelligence guy, the image in his rear view mirror is not reversed.