(incorrectly regarded as goof) Freddy says Marge is 5'3", but a police dispatcher says she's 5'5". This isn't necessarily a mistake, as both were making a guess based on eye contact.
The scene in which Freddy is watching Marge remove her 'Sadie' wig to reveal her fluffy blond hair involves a well-done substitution splice, presumably because to get the Sadie wig to fit realistically, Marion Davis' real hair would have been tightly slicked or tied down.