Gaffes

In the film's funeral home scene when Joseph Carter first walks in, he is seen from the waist down and he is wearing a long blue coat. When a full view of Carter is shown, he is neither wearing nor even carrying a long blue coat. However, Mr. Martin, outside the funeral home, is now wearing the coat that was originally worn by Carter.

When the rats are tearing up the newspaper, the amount of damage that is done to it by them is inconsistent. At one point, they have torn it all the way through to the blue banner at the top of the page; later, it is intact again.

Willard lays out some glue strips to catch the rats. A rat steps on one and gets stuck. When Willard first sees it, the rat is only glued on the bottom three-quarters of its body. Its front legs are free and it is crawling away with its belly and lower legs flattened onto the strip. Then Willard decides to save its life. In the next shot of the rat, all four feet are on the glue strip with its belly raised up. It is also in the center of the glue strip, whereas before it was hanging off one end of it.

When Willard is playing with the spring trap, it is baited in the long shots, but it is not baited in the close-up shots.

The sex of the two main rats, Socrates and Ben, changes throughout the film. In some scenes, the rats are male and in others, they are female.

The coroner's printed form listing Willard's father's personal effects is misspelled "Personal Affects".

After Martin has been killed, Cathryn comes over to Willard's house to let him know about Martin's death, not knowing that Willard was behind it. Since Cathryn was only a temp with the company, and had walked out earlier that day, it seems odd that she would have gotten this information to pass on to anyone employed with the company.