Interesting story: the Rosebud sled is an inside joke. William Randolph Hearst's pet name for his girlfriend Marion Davies was Rosebud (which was after a certain part of her anatomy) and a sled was a rude name for a woman you were having sex with. It was allegedly for this veiled insult to Marion Davies that Hearst went after Orson Welles, not his depiction of Hearst as Kane. Or so the story goes.
Ah, well that makes sense then.