During the Credits
There is a tribute to Stan Lee shown during the credits of Spider-Man: Into the Spider Verse.
After the Credits
There is an extra scene after the credits of Spider-Man: Into the Spider Verse.
In the extra scene, Spider-Man 2099 from Earth 69 (an old cartoon series) and Spider-Man recreate the popular meme of accusing and pointing at each other.
Special thanks to James Kite for the stinger submission!