In The Amazing Spider-Man 2, the clock tower strikes 1:21 and Gwen Stacy falls to her death. This is a reference to the 1973 issue #121 of the comic book series in which Gwen dies.
That's 1 of 10 impressive Easter eggs hidden discreetly in superhero movies, including the 1978 Superman and the 2008 film The Dark Knight. Learn about all of them in this new video by Screen Rant.