Actor Walter Olkewicz's name is misspelled 'Oklewicz' in the opening guest cast.
In the beginning at breakfast with Agent Cooper, Sheriff Truman, and Lucy, Agent Cooper's left hand is pouring syrup on his breakfast while Truman is talking, though no syrup comes out of the container. When Agent Cooper is shown next, the syrup container is shown on the right side of his body, which is a flaw since Cooper used his left hand and placed it on what would be his left side of the table. Also, syrup can be shown on his breakfast.
In a diner scene between Agent Cooper, Sheriff Truman, Big Ed, and Deputy Hill, the Sheriff's hat can be seen disappearing and reappearing on the table between dialogue cuts on each side of the booth.
When we see Audrey Horne prior to Laura's funeral, her hair is parted on the left side. At the funeral, her hair is parted on the right side.
In the funeral scene, Major Briggs' cap badge is worn only by enlisted US Air Force personnel, as an officer he should have a different cap badge (larger eagle device instead of a smaller one enclosed in a circle).
When Leland Palmer tells his wife to tell the police about her visions his mouth does not move when he says "Go ahead Sarah".