this is a collection of facts you probably never knew. they are interesting and are worth reading.

  In this film, Anthony Sharp plays a government minister. In Stanley Kubrick's later film, Barry Lyndon (1975), he plays a former minister, Lord Harlan.  
To film Alex's suicide attempt from his own perspective, a Newman Sinclair camera enclosed in a custom built plastic box was thrown off a building six times until it finally landed pointing downwards. It broke the lens of the camera, but the camera survived otherwise unscathed! Kubrick later marvelled at the durability of this particular type of camera
Many actors play multiple roles.
Alexander's bodyguard was played by professional bodybuilder David Prowse. Even so, he was near exhaustion after the repeated takes of him carrying Alexander and his wheelchair down the stairs.
The photo-montage when Alex clobbers the old lady are mostly the paintings the old lady has hanging in her room
The newspaper article gives Alex's last name as "Burgess".
Many phallic references: snake crawling between the legs of the woman in the poster, the popsicles held by the girls in the record store, the tip of Alex's walking stick, the object used by Alex to kill the woman.
Malcolm McDowell chose to sing "Singin' In The Rain" during the rape scene, because it was the only song he knew all the lyrics to.
The book that Frank Alexander is working on when Alex and his droogs break into is home is called "A Clockwork Orange". Author Anthony Burgess uses a pun on the Malay word "Ourang." Burgess lived for several years in Malaya. The attack on his wife was based on an attack on Burgess' wife by four American GIs during WWII, which caused her to miscarry.
The tape that Alex removes from his stereo in order to play Beethoven bears the name of fictitious artist Goggly Gogol, mentioned later by one of the popsicle girls on the music store.
2001: A Space Odyssey (1968) (also directed by Kubrick) soundtrack highly visible in record store.
The film rights were sold for "a few hundred dollars", but then re-sold for a much larger amount. Before director Stanley Kubrick become involved in the film, several different casts were considered for Alex and his droogs: girls in miniskirts, old-age pensioners, and The Rolling Stones.
The snake, Basil, was introduced into the film by Kubrick when he found out McDowell had a fear of reptiles.
During the filming of the Ludovico scene, star Malcolm McDowell scratched one of his corneas and was temporarily blinded. He suffered cracked ribs during filming of the humiliation stageshow, and he also nearly drowned when his breathing apparatus failed while being held underwater in the trough scene.
In the book, Alex's last name is never revealed. "DeLarge" could be a reference to a line in the book in which Alex calls himself "Alexander the Large" while raping two 10-year-old girls (in the movie they are much older).

When Alex and the droogs enter the Korova Milkbar, there are many paintings on the wall, one of a naked woman. This same painting appears in Shining, The (1980), also directed by Stanley Kubrick.

The first line the prison minister says in the film, "What's it going to be then, eh?" is also the first sentence of the novel.
The budget for the film was $2 million.
Kubrick insisted the milk in the milk dispensers were emptied, washed, and refilled every hour (the milk curdled under the studio lights).
The sculptures in the Korova Milkbar were made by sculptress Liz Jones.

Kubrick once said "If Malcolm [McDowell] hadn't been available I probably wouldn't have made the film."

Directors Trademark (Stanley Kubrick): [faces]: Alexander, when he realizes who Alex is.
Directors Trademark (Stanley Kubrick): [three-way]: Alex vs Government vs Alexander.
Directors Trademark (Stanley Kubrick): [114]: Alex is given "Serum 114" when he undergoes the Ludovico treatment.
Dim and Georgie as policemen have badge numbers 665 and 667. This makes Alex, in the middle, 666.
Many of Alex's slang words are taken from Russian, including droog (friend), malchick (boy), korova (cow), and moloko (milk).
The film leaves out chapter 21 of the book, where Alex starts thinking about getting married and settling down. Burgess said: "A vindication of free will had become an exaltation of the urge to sin. I was worried. The British version of the book shows Alex growing up and putting violence by as a childish toy; Kubrick confessed that he did not know this version: an American, though settled in England, he had followed the only version that Americans were permitted to know. I cursed Eric Swenson of W. W. Norton (the US publisher)."
The film was withdrawn voluntarily by Kubrick from the United Kingdom after being criticized as too violent. Kubrick has stated that the film will be released there only after his death.
Kubrick deliberately made continuity errors just before the author worked out who Alex is. The dishes on the table move around and the level of wine in the glasses change between shots to give a feeling of disorientation to the viewer.
The language spoken by Alex and his droogs is author Anthony Burgess's invention, "Nadsat": a mix of English, Russian and slang. Stanley Kubrick was afraid that they had used too much of it, and that the movie would not be accessible. (He need not have worried.)
The name of the film, A Clockwork Orange, is based on a colloquial British expression, "as queer as a clockwork orange," meaning a mechanical piece of fruit. The title was almost completely lost on American audiences.

obtained from internet movie database