Creator Backlash: Welles wasn't that big on the film. He preferred some of his later work, like his adaptation of Kafka's The Trial. In a 1960 interview, he said, "I'm ashamed of Rosebud. I think it's a rather tawdry device. It's the thing I like least in Kane. It's kind of a dollar-book Freudian gag, you know. It doesn't stand up very well."
Creator Killer: The "Greatest Movie of All Time" was also the movie that killed Welles standing as a director in Hollywood. Prior to Citizen Kane, Welles himself was very much a victim of the Hollywood Hype Machine and when the movie bombed at the box office, no studio would allow Welles complete creative control over any more of his films. Subsequent flops would serve as the death nail to his career.
Dyeing for Your Art: To simulate heavy drunkenness, Cotten stayed awake for 24 straight hours, resulting in some unscripted flubbery (that caused Welles to grin despite himself).
One Steve Limit: Averted. The film has characters named Jim Gettys and Jim Kane.
Star-Making Role: Kane was a Star Making Role to some extent for most of the cast, since the bulk of them were members of Welles' Mercury Theater troupe and they were all making their film debuts together.
Joseph Cotten went on to a long and very successful career as a leading man in Hollywood.
Welles himself is an interesting aversion. He was a star since age 16, and became famous for his theatre and (cough) radio, and had in fact made three films prior to this (a bizarre short in 1934, a 40-minute film that was intended to be part of a hybrid stage play/movie performance in 1938, and he narrated a version of Swiss Family Robinson a year before Kane came out), but the movie almost destroyed his career.
Sadly averted for Dorothy Comingore, who delivered a powerful performance as Susan Alexander but saw her career derailed by alcoholism and poor decision-making even before it was permanently ended when she was put on the Hollywood blacklist.
Throw It In: Joseph Cotten stumbling over the word "criticism". It was a genuine flub, but fortunately both he and Welles stayed in character (albeit Welles grins) and Cotten follows up with a brilliant ad-lib "I AM drunk", so it stayed in the film as-is.
Welles was originally going to make an adaptation of Joseph Conrad's Heart of Darkness but the executives didn't believe they could possibly stretch a budget far enough to cover it, so he made ''Kane'' instead.
Word of Dante: Sort of. People assume Marion Davies had a bad career, as her expy in the film shows. In fact, Marion Davies was widely considered a talented actress and comedienne, independent of all the publicity Hearst arranged for her. Hearst did push Davies towards melodramatic leading-lady roles. Davies - along with many others - recognized that her real gift was for light comedy.