Kubrick's film is relatively faithful to the Burgess novel, omitting only the final, positive chapter, in which Alex matures and outgrows sociopathy. While the film ends with Alex being offered an open-ended government job, implying he remains a sociopath at heart, the novel ends with Alex's positive change in character. This plot discrepancy occurred because Kubrick based his screenplay on the novel's American edition, in which the final chapter had been deleted on the insistence of its American publisher.[85] He claimed not to have read the complete, original version of the novel until he had almost finished writing the screenplay, and that he never considered using it. The introduction to the 1996 edition of A Clockwork Orange says that Kubrick found the end of the original edition too blandly optimistic and unrealistic.
- Critic Randy Rasmussen has argued that the government in the film is in a shambolic state of desperation, whereas the government in the novel is quite strong and self-confident. The former reflects Kubrick's preoccupation with the theme of acts of self-interest masked as simply following procedure.[86]
- In the film, Alex has a pet snake. There is no mention of this in the novel.[87]
- In the novel, F. Alexander recognises Alex through several careless references to the previous attack (such as his wife then claiming they did not have a telephone). In the film, Alex is recognised when singing the song 'Singing in the Rain' in the bath, which he had hauntingly done while attacking F. Alexander's wife. The song does not appear at all in the book, as it was an improvisation by actor Malcolm McDowell when Kubrick complained that the rape scene was too "stiff".[88]
