The road to Thanos gathering all six infinity stones in Infinity War was long, but the road to Who Framed Roger Rabbit? was the biggest clash of egos in animation. In 1985, then-new Disney CEO Michael Eisner revamped a dead project about an adaptation of Gary K. Wolf’s 1981 novel Who Censored Roger Rabbit? Before coming to Disney, Eisner had served as head of production at Paramount Pictures, where he worked with Spielberg and George Lucas on Raiders of the Lost Ark. Spielberg returned the favor and agreed to help produce Who Framed Roger Rabbit? and to bring along Lucas' team of visual effects wizards from ILM — as long as Amblin Entertainment and Disney split the box-office takes and licensing rights 50-50.

In return, Spielberg was able to convince Warner Bros., King Features Syndicate, Felix the Cat Productions, Turner Entertainment, Fleischer Studios and Universal Pictures/Walter Lantz Productions to lend their characters for the unbelievable flat rate of $5,000 per character, with minor stipulations (such as Warner Bros. demanding Bugs Bunny to appear only in scenes opposite Mickey Mouse and with the same amount of screen time).

The result was the most ambitious project in the history of American animation. Yes, there were other films that integrated cartoon characters with live-action performers, like Mary Poppins and Pete's Dragon, but none felt as real as when fictional cartoon tycoon R.K. Maroon (Alan Tilvern) gives Roger a handkerchief and he cleans his nose with it. This was the first time that a movie like this was made to serve the cartoons first and the people second. The cartoons cast real shadows, seem to occupy real space and look three-dimensional before computer animation became dominant. If this movie was only about its technological achievements, as impressive as they are, it might feel like a dated relic today. Instead, Roger Rabbit does what all the best movies with revolutionary technology do — it treated the effects as a tool for telling a story.

Spielberg's Ready Player One got strong reviews early this year that praised its visual effects and performance capture. However, critics noted that while the movie was highly entertaining, it had narrative weaknesses, and argued that the cameos came before the story, with a lack of depth for its characters.

In contrast, Who Framed Roger Rabbit? has a clear and enthralling story in mind that works with or without the cartoons. Detective Eddie Valiant (Bob Hoskins) is hired to investigate if Jessica Rabbit (Kathleen Turner), wife of toon star Roger Rabbit (Charles Fleischer) is having an affair, and soon the innocent Roger is framed for murder. There's also the Cloverleaf streetcar subplot that was inspired by Roman Polanski's Chinatown, but which also has parallels to the real-life General Motors streetcar conspiracy that saw an alliance of companies that schemed to bring down Los Angeles' rail network in favor of buses and automobiles. Add this all together and you have the perfect way to introduce kids to the hard-boiled crime movies of the 1940s.

Beyond its triumph in animation techniques, Roger Rabbit is best known today for featuring an unprecedented number of cameos from known cartoon characters. Not only are Mickey Mouse and Daffy Duck in the movie, but so are Dumbo, Yosemite Sam, Speedy Gonzales, Droopy, Felix the Cat, Woody Woodpecker and many more.

This was far from the first crossover in film, but while Abbott and Costello did meet Frankenstein, The Lego Movie featured Dumbledore and Gandalf fighting, and Ready Player One had Batman fight alongside the Iron Giant, most of those properties already belonged to the company producing the movie. Marvel did get Sony to allow Spider-Man to appear in Captain America: Civil War, but with Roger Rabbit, Spielberg did the impossible by convincing seven of the biggest egos in the animation to lend their characters for a once-in-a-lifetime movie event. Nothing can compare to seeing Bugs Bunny and Mickey Mouse onscreen together — that is until someone greenlights a Justice League/Avengers movie.

Infinity War was sold as the biggest crossover event in history, a cultural event of epic proportions that was so big it had to be split in two. Yet Roger Rabbit didn't need to be sold as a cultural milestone — it just was. The movie feels special because it doesn't make a big deal out of all its characters and personalities, they are just there as normal citizens of Toontown. The insane number of cameos could be considered excessive, but Who Framed Roger Rabbit? doesn't draw more attention to them than it does to the human citizens of Hollywood (with the exception of Bugs and Mickey, because they are Bugs and Mickey). In Avengers, each character is given a lengthy hold for applause when they first arrive onscreen, showing the audience how big of a deal it is to see these characters together. When we see Dumbo in Roger Rabbit, he is just another actor.

"The best part is, they work for peanuts," proclaims studio head R.K. Maroon as he throws peanuts to the flying pachyderm. Betty Boop may not be a big part of the plot, but seeing her working in a nightclub and complaining about the lack of jobs for black-and-white characters feels natural.

Today, most blockbusters are pitched like a big cultural event. Maybe more studios should look at the tale of a cartoon rabbit framed for murder as a goal of how to do it right, not by shoving in as many cameos as you can, nor by having the biggest visual effects spectacle you can afford, but by using those tools as a means to tell a good story. Who Framed Roger Rabbit? isn't just an homage to American animation and 1940s detective films, it is a great animated film and a great detective film by itself.