Continuity mistake: Magnum is talking with Mr. White, hands raised, for some reason. When the camera is behind Tom Selleck, his two forefingers of the right hand are close together, while filmed from the front they distant enough to keep the index out of frame entirely. (00:15:30)
Revealing mistake: The security guy is checking Magnum as he appraises the cutlery and waits with his client for the rich man. And at the top of the frame of the security camera feed...the security camera that is supposedly filming. (00:14:40)
Continuity mistake: The chauffeur gets a phone call while Magnum and his client is in the elevator. In wide shot he's holding the wheel with the hand at the top, but he's waiting with the hand on 9 o' clock in the closer view, and back on top as it switches to the same angle as before. (00:13:20)
Continuity mistake: The guy on top of the building passes TC an envelope with his fee. The envelop is facing a different direction between shots - it opens with the flap towards him in the first one, towards TC in the next. (00:02:40)