Disorganization is rampant so lots of time and resources are wasted. Often completely separate teams end up working on the same project because neither knew about the other. Likewise, projects and research that have already been done tend to get done over and over because the information is not disseminated appropriately. Major projects tend to get spun up rapidly and dropped just as fast because of this disorganization, so a majority of the really big and cool things people work on here never get completed and see the light of day.
Leadership is often inexperienced and ineffective. Most senior leaders surround themselves with yes-men only and challenging the wrong leader can effectively end your career at Riot. Subordinates often end up getting scapegoated for poor leadership decisions while the leaders themselves get off scot-free. Leadership also tends to claim that we have the "secret sauce" but no real idea what it actually is, which leads to sitting around twiddling our thumbs.
Can be a hostile workplace. People who come forward with complaints or stories about discrimination tend to get brushed off as "poor culture fits" or "not core gamers" (including by senior leadership). Casual sexism, racism and transphobia is pretty rampant here.