A classic example from From Here to Eternity:

In the novel, Captain Holmes ironically receives his desired promotion, and is transferred out of the company. In the film, Holmes is forced to resign from the Army under threat of court-martial for his ill-treatment of Prewitt. The Army insisted on this change, which the filmmakers reluctantly made. Director Zinnemann later complained that the scene where Holmes is reprimanded was “the worst moment in the film, resembling a recruiting short”, and wrote, “It makes me sick every time I see it.”