If you hit pause anytime a train goes by, because all the animators wanted to animate Stan Lee, he's in almost every single train.
It was Peter Ramsey's idea to hold off on the visual comic language - word bubbles, panels, etc. - until Miles is bitten by the spider.
It was announced shortly after Stan Lee's death, at age 95, that he had recorded a cameo for the film and that it would be his final voice-acting role. Phil Lord and Christopher Miller felt it was important that Lee was given a bigger moment compared to previous Marvel films because he was "so integral to the spirit of this movie," and considered his role "extra meaningful" following his death.
Art directors Dean Gordon and Patrick O'Keefe and their team turned to Cubism to help represent the dimensional quakes. Cubist art often presents a collection of different views all happening at the same time, so it was a natural metaphor for the multiple universes converging in "Spider-Verse."
The unique animation style of "Spider-Verse" aims to make the viewer feel as if they are in the pages of a comic book. According to Phil Lord and Christopher Miller, the film combined the latest computer-generated animation technology with hand-drawn artistry. "It was very important to us that every frame of the movie was refined by the artist's hand after the visuals were rendered by computers. If you freeze any part of the movie at any time, it will look like an illustration with hand drawn touches and all."