Continuity mistake: During the visit of the Minister in jail, Charlie sits next to the Minister's wife. The distance between them varies between shots. (00:30:40)
Continuity mistake: In this scene we see several Government Officials talking in a room. One of them, while talking, is playing a game. The game is to balance the lid of an ink bottle on the end of a ruler and over the ink bottle. When the ruler is flicked rapidly gravity would do the rest and the lid would fall into the ink bottle. Things don't work to plan and the lid falls on its side. In the next wide shot, the lid is right side up and a little distant from where it fell earlier.
Continuity mistake: The lawyer and his two collaborators arrive in Mandrake Falls and reach Longfellow Deeds' home. The housekeeper opens the door to let them in...and never bothers to close it (and it does not close by itself). Few seconds later, Deeds' arrival is announced by the dog who impatiently paws at the closed door. (00:04:50)