Mar-Vell’s cat is a crossover from Lovecraft’s universe of Elder Gods. In fact, Goose is an anagram of Cthulhu, which is a subtle nod to my inability to spell and ignorance of what, exactly, an anagram is.
When it rains, some members of the rag-tag group of superheroes use umbrellas to keep dry. This is a subtle nod to the eponymous series title, Umbrella Academy.
When the school nurse has to cut Gwen’s hair to free her from Miles, the hair left on Miles’ palm is a subtle nod to his pubescent pursuit of the masturbatory arts.