Rick and Morty season 5 humorously referenced Robert Downey Jr. to make a point about human nature — but Community actually used a similar joke to make the same point. The world was yet again brought to the brink of destruction, this time due to Morty's grim misuse of veterinary equipment, in Rick and Morty season 5, episode 4, "Rickdependence Spray." As a result of Morty's egregious teen libido, a conflict arose with rampaging, sentient sperm and even featured a race of cannibalistic horse people known as CHUDs.
When the truth of Morty's culpability was exposed, he was understandably berated by everybody involved. During one particular reproach from Rick, Morty sullenly snapped, "I can't change my nature." Rick immediately scoffed at that notion, declaring that the ability to change was what defined the human race. To emphasize his argument, Rick cited Robert Downey Jr. as an example. "Look at Iron Man. That actor was an animal in the '90s, literally waking up in bushes. His agent had to catch him with a butterfly net." Rick and Morty were then silenced by the horror movie-referencing CHUDs but the point hilariously remained.
It actually wasn't the first Dan Harmon-related show to make both that exact reference and point, however. Instead, that honor went to Community. In season 6, newcomer Frankie Dart (Paget Brewster) led the charge on trying to improve Greendale. During the paintballing antics of Community season 6, episode 11, "Modern Espionage," though, The Dean (Jim Rash) doubted the capacity for a better Greendale, likening the school to tobacco. Jeff Winger (Joel McHale) similarly rebuked the idea. "No, we are not tobacco. We are Robert Downey Jr. He was so high, he was crawling into people's windows. Now he's Iron Man!" Jeff then went on to further illustrate how growth was possible — albeit with a lot of commitment and dedication to actually doing the work.
The point was a valid one, in both cases. In actual fact, it could equally be attributed to Tony Stark as much as Downey Jr. Initially a selfish, reckless playboy with little care for the wider world, Tony Stark ultimately overcame his flaws enough to be a hero that saved the entire universe in Avengers: Endgame. The fact Downey Jr. embarked on a real-world redemptive journey was one of the many reasons why he was singularly perfect for the Iron Man role. Given (the similarly redemptive) Harmon's role in both shows, it was equally no surprise that the point was one worthy of being repeatedly made. Furthermore, it continued the kind of overlap that previously saw Rick and Morty include a Community easter egg.
The reference was also one that poignantly tied into Rick and Morty season 5's larger themes. Multiple episodes have seen Rick reckon with parts of himself. He reconnected with his capacity to love and commit to somebody - first with the alien Daphne (Jennifer Coolidge) and Princess Ponietta (Christina Ricci). A version of him actually recognized and apologized for his faults. The episode in question even saw Rick admit he had a substance abuse problem — an important first step in recovery. As such, it added to the idea that Rick might not always be the villain of his own story. Plus, it lent credence to Rick and Morty season 5, episode 4, "Rickdependence Spray" being secretly a smart episode within the show's overall run.