Melissa has a flashback to the first day of summer when she was making a science project in her backyard when a rollercoaster suddenly was dropped from a helicopter resulting in her fear of rollercoaster. This alludes to the first Phineas and Ferb episode where Phineas and Ferb build a roller coaster that's suddenly taken away by a helicopter with a magnet.
At the beginning of the Murphy's trip, there's a song montage that starts with a map showing their progress. It shows their RV icon going east on I-70, leaving a city that has an I-270 beltway around it. This would place them east of Columbus, OH.