Laputa: Castle in the Sky: Fox squirrels from Nausicaa make an appearance. A church tower is destroyed.
My Neighbour Totoro: A roadside shrine is used as a rain shelter and another shrine is shown as derelict.
Kiki’s Delivery Service: Studio Ghibli on a bus advertisement. In Kiki’s bedroom there is a toy house in her bookshelf and Mei and Chibi-totoro are painted into the windows. A church tower is destroyed. In the scene at the end where the street-sweeper is pointing at the TV and saying “that’s my broom she used”, Miyazaki is in the upper-right corner of the picture looking on.
Porco Rosso: Ghibli embossed on engine cylinder block. Ghibli restaurant sign in Milan in the truck scene. Some the character names have aircraft references (e.g. Donald Curtiss).
Ocean Waves: In the train station at the end of the movie, there is a Porco Rosso movie poster on the wall. Porco also shows up in the school festival scene.
Pom Poko: Porco, Kiki, Totoro, and Taeko appear in the scene where the Tanukis are heading for the town to conduct the “Monster Parade”. A younger Kita and Minami (and maybe even Shizuku’s parents as kids) appear in one crowd scene in the parade. Shrines are seen being destroyed.
Whisper of the Heart: (lots in this movie) Porco Rosso on the clock. Chibi-Totoro, a chu-Totoro and Jiji appear in one of the fantasy scenes in the dollmakers shop. “Mimi wo Sumaseba” advertisement on a building. The book Seiji is reading in the library the night he leaves for Italy is one of the books that inspired Spirited Away. A book in the school library has “Totoro” on the spine. The whole movie is full of accurate calendars etc, you can fix the exact start and end dates, and the dates of most of the important scenes. Mr Nishi’s grey van appears in only two scenes, the steering wheel is on different sides in the two scenes. A shrine appears in two romance scenes. The names of the three musicians Nishi, Kita and Minami mean West, North and South respectively. Whatever happened to Mr.East (Higashi) I wonder?
Spirited Away: Susuwatari from Totoro make an appearance.
Howl’s Moving Castle: Pazu appears briefly outside Wizard Jenkins house.