Revealing mistake: During the gun prank, you can see in the revolver's cylinder the bullets - except when it squirts, the bullets are gone. (00:47:00)
Revealing mistake: When the plane is blowing dust all over the lawyer and the money-conscious nephew, you can see the face of the extra piloting the plane instead of Donnelly Rhodes. (00:03:50)
Revealing mistake: Magnum takes an ancient gun from the cabinet and stumbles upon one of the eccentric millionaire's practical jokes. The joke though is an impossible one; the string that supposedly triggers it is not there, and when the gun goes off, Magnum is not holding the gun in a way that would pull it. (00:16:25)