But that’s not all. One of the weird trademarks of Clone High is that it had either a dolphin or a dolphin sound in every episode, and Phil Lord and Chris Miller have kept that tradition going during their movie career. All of their movies, both animated and live-action, have included the sound of a dolphin, and that includes Spider-Man: Into The Spider-Verse (even though they didn’t actually direct it). It’s not immediately noticeable, as I actually didn’t catch it during my first viewing of the feature, but according to the writers/producers it can be heard during all of the massive chaos in the big climactic third act fight sequence.
Article source: https://www.cinemablend.com/news/2463905/phil-lord-and-chris-miller-snuck-some-personal-easter-eggs-into-spider-man-into-the-spider-verse