FYI for anyone playing the game and getting stuck trying to find access to the roller coaster. I checked out the video walkthrough (thanks to Marian) and found that I did not trigger an event. After riding the ferris wheel and seeing the tree blocking the path to the roller coaster, right beside the tree is a broken ride car. I previously looked at it but did not look inside it. When you look inside it, there is a ticket which, when clicked, will trigger an event unblocking the pathway.
On with the game!