The residents of Gotham learning even if The Joker gets hit by a billion stars exploding, he won't die for good because he is a popular character and killing him off for real risks damaging sales:
I find it interesting that Mike Tyson's Punch Out has not been sold for multiple decades but whenever Punch Out gets a shout out on a tv show or movie it's always that specific version
Just so you know, Rugrats in Paris is currently free on YouTube, really good movie (Get an ad blocker first though if you don't want to be constantly interrupted)