When the Baron is narrating the history of his world one of the cat people is dressed like Nausicaa, this is a reference to one of Miyazaki's earlier films "Nausicaa of the Valley of Wind".
When Shizuku is working on her book, you can see over her left shoulder a witch on a broomstick, this is a reference to one of Miyazaki's earlier films "Kiki's Delivery Service".