Sumedha Ganjoo presented on common mistakes made when adopting Scrum. She discussed how having one person act as both the product owner and Scrum master leads to conflicts of interest and less accountability. Other mistakes include not properly estimating work, allowing technical debt to accumulate, focusing on documentation over working software, and customizing Scrum practices without understanding the reasons behind them. The presentation emphasized separating roles, setting clear expectations, prioritizing working software over documentation, and making incremental improvements based on team feedback and retrospectives.