When a guard asks Jack to kneel, he replies that he can't as he has trouble with his knees. This stems from the fact that Richard Dean Anderson actually does have knee trouble in real life from injuries playing hockey as a teenager.
When Jack says 'The man who would be King', he is referencing the film "The Man Who Would Be King (1975)" starring Sean Connery and Michael Caine (based on the short story of the same name, by Rudyard Kipling). The film is about a normal man (Connery) who becomes a king and is slowly brainwashed by his own power, damaging his friendship with Caine's character in the process.