Well, it started with security lines being completed backed up. Runners couldn't get through the security lines to get to the race corrals in time. If you went to bag check, you had to go through security twice. The corrals were overly crowded; they should have made more corrals. This made the course more crowded than usual. There was little race etiquette used by other runners, which I know rD cannot enforce, but I did mention this as a safety issue. As someone having foot surgery a few days after the race, I was a slower runner. I stayed to the right like I am supposed to do, but runners who stopped for pics raced up the right hand side to make up time, tripping over me or almost making me trip and fall, making the situation a bit dangerous, especially in the parks where the course where was crowded. They changed the course, we ran in some of the DL parking lots....boring; they didn't have any fun things out in the backlots like they usually do; there weren't any characters out for the 5K (I didn't do the 5K, but I heard about this). There wasn't any course entertainment when we were out in the City of Anaheim, I missed seeing the cheerleaders and bands, etc.
Here is an article that gives a review of some of the other problems:
https://www.mouseplanet.com/11776/Changes_Cause_an_Uproar_at_2017_Tinker_Bell_Half_Marathon_Weekend