- Movie Goof (revealing mistake): When the water breaks through the wall, near the end of the movie, you can see that the wall is made out of Sheetrock and not plaster keyed to lathe which would be appropriate to the house's age.
- Movie Goof (continuity error): In the scene where Alexander Falko hands the check for ten million dollars to Ernie, after writing the check he puts the pen on the table and in the next shot the pen suddenly appears again on his hand.
- Movie Goof (errors made by characters, possibly deliberate errors by the filmmakers): The length of Ernie's hair changes between shots.
- Movie Goof (continuity error): The bite marks in the vegetarian snack that Alexander Falko bites into, disappear throughout the next shots of him biting into it.
- Movie Goof (crew or equipment visible): In the scene when Lars is alone inside the factory, you can clearly see an arm behind the big fan pulling the thread from his jacket. You can even see a watch on the arm.
- Movie Goof (revealing mistake): When the vacuum cleaner is attached to the sewage line, the mouse watches from outside. He sits on top of the upper ("outer") window panel which has been pulled down to the bottom position of its track (for easier cleaning - consistent with the boys housecleaning). Based on interior and exterior shots in the scene, the lower ("inner") window panel appears to run the entire length of the window. In addition, the position of the curtains change from framing the window to pulled back.
- Movie Goof (revealing mistake): In the shot when Ernie and Lars head to the factory and we see the striking workers outside the building, a cargo container and a palm tree that are off-set are clearly visible to the left of the screen.
- Movie Goof (revealing mistake): When Ernie is shot through the chimney into the nearby lake, ear plugs are visible once he sinks down on the bath tub.
- Movie Goof (continuity error): SPOILER: In the scene where Ernie is loading the shotgun to kill the mouse, he knocks over a lamp with the shotgun. But shortly after that, the lamp is standing upright, and in the next shot, the lamp is down again.