The bite marks in the vegetarian snack that Alexander Falko bites into, disappear throughout the next shots of him biting into it.
When the Mayor spits out the half eaten cockroach it stumbles out of a creamy sauce on the table cloth. In the next scene it is walking on a clean table.
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.
The speed of the orange after it hits the mouse.
In one scene it is spinning slowly in the next it is spinning faster and in the next it is not spinning at all.
In one scene it is spinning slowly in the next it is spinning faster and in the next it is not spinning at all.
The length of Ernie's hair changes between shots.
Once the package containing the mouse arrived back at the house's doorstep, the mouse would have froze to death or died of suffocation after two flights in the cargo hold of a commercial airliner.
The package containing the mouse having insufficient postage due to it's weight would have be discovered at the post office the package was dropped off at who would have then returned it.
Furthermore, had the insufficient postage slipped through the cracks until Cuba, the package would have been either forwarded to the intended recipient who would have to pay the remaining fees from the postage or it's contents would have been destroyed, rather than paying to have it sent all the way back to the US.
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.
When Ernie is shot through the chimney into the nearby lake, ear plugs are visible once he sinks down on the bath tub.
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.
The chimney Ernie gets stuck in wobbles a few times as he is climbing it.
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.
The word "foreclosure" is misspelled in the notice being nailed to the front door.
When the mouse and the cat run across the piano during their chase, the cat presses down certain piano keys. However, the pitches made by such keys are not present in the film's soundtrack.
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.
In the closeup of Ernie looking out the restaurant door window after the mayor is put in the ambulance, the matte box is reflected in the window.
When Ernie and Lars are arguing, Ernie mentions that he made his special rack of lamb for Rudolph's 70th birthday, and the only thing Rudolph noticed was the string Ernie tied it with. A rack of lamb consists of 7-8 lamb ribs and does not require tying. The only cut of lamb that does require tying is leg of lamb.