Complex sentence: When Rhodes comes onto a case to observe Beckett, Castle is further insulted that she has not read the actual book, he is considered unimportant to the film and Beckett likes having Natalie around.
Split into simpler sentences: When Rhodes comes onto a case to observe Beckett, Castle is further insulted that she has not read the actual book. Rhodes considers him unimportant to the film and Beckett likes having Natalie around.