kubricksfilms:

Stanley Kubrick and Malcolm McDowell on the set of “A Clockwork Orange” (1971).

Alex “popping” his mouth open for food was entirely improvised, as Stanley Kubrick got incredibly bored during the scene and Malcolm McDowell started acting silly just to keep everyone’s attention focused.

Before filming the scene where he had to carry Patrick Magee’s wheelchair up the stairs, professional bodybuilder David Prowse went up to Stanley Kubrick and asked if he could make sure that (due to the difficulty of the task) he got the scene in as few takes as possible, saying, “You’re not exactly known as ‘one-take-Kubrick’, are you?” The rest of the crew was horrified at such a famous director being talked to like this, but Kubrick just laughed and promised to do his best. The scene was filmed in only three takes, an incredibly small amount for a perfectionist like Kubrick. Even so, Prowse was near exhaustion after the repeated takes of him carrying Frank and his wheelchair down the stairs.

In the police station scene when Mr Deltoid (Aubrey Morris) spits in Alex’s face, it is actually Steven Berkoff doing the spitting. After several takes, Morris complained to Stanley Kubrick that he had run out of saliva, and Berkoff volunteered his services until Kubrick’s cameras captured the perfect ‘spit-shot’.

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 stage show.

Alex performing “Singing in the Rain” as he attacks the writer and his wife was not scripted. Stanley Kubrick spent four days experimenting with this scene, finding it too conventional. Eventually he approached Malcolm McDowell and asked him if he could dance. They tried the scene again, this time with McDowell dancing and singing the only song he could remember. Kubrick was so amused that he swiftly bought the rights to “Singing in the Rain” for $10,000.

When McDowell met Gene Kelly at a party several years later, the older star turned and walked away in disgust. Kelly was deeply upset about the way his signature from Singin’ in the Rain had been portrayed in the film..

According to Malcolm McDowell (on the commentary track from the 2007 DVD release), the sped-up sex scene was originally filmed as an unbroken take lasting 28 minutes.