George Clooney plays Lieutenant Scheisskopf, who was a minor character in the book (although Chapter 8 is named after him). But Lieutenant Scheisskopf is not portrayed in the 1970 motion picture.
Kyle Chandler plays Col. Cathcart, who was played by Martin Balsam in the 1970 film. Martin Balsam would become George Clooney's father-in-law when Clooney married his daughter, actress Talia Balsam, from 1989 to 1992.