Trivia: In the scene where Alex approaches the two girls at the record stand you can see the original score for 2001: A Space Odyssey, also directed by Stanley Kubrick.
Continuity mistake: Look at the scene where Alex beats Georgie and Dim and they fall in the river. Alex politely offers his hand to Dim, and in the background you can see Georgie with no hat. Shortly afterwards, he's got his hat on.
Continuity mistake: When Alex is informed that he's being transferred to the Ludovico center, the governor's arms jump from his lap to under his chin, then back to his lap. (01:06:00)
Answer: Since this is a futuristic police state, it's likely that Mr. Alexander was dealt with the way dissenters are often dealt with in such situations (Execution or lifelong imprisonment.). In the book, he wrote literature protesting the police state. (The phrase "A Clockwork Orange" comes from a pamphlet he wrote.) Alex and his droogs kicked and beat him while they raped his wife. A while later, the doctors told him she'd died of pneumonia, but he thinks the trauma made her give up the will to live.