Early on, when the guy sits down at the table in the bar with the Kacey, the ash on his cigarette is longer in the first shot than in subsequent ones.
After Kelly pulls his gun on Magnum, you can see the shadow of Vic Morrow getting into position for his part in the scene.
As Magnum walks through the jungle looking for Nick, the camera brushes against a branch and causes it to move noticeably.
After officer Kelly and Jordan drives away from the Surfer Club, when Magnum opens his Farrari door to get into the car, you can see crew in the driver side view mirror while the door is open.