Peter had tried to use the roller coaster but due to his weight, the cars were unable to make the first drop. At the end, as a peace offering, he and Ezekiel were enjoying the roller coaster without any problems.
When the Griffins enter their humble accommodations for their night stuck in Amish country, it is shown to be nighttime through the room windows as Eli, Meg's soon-to-be romantic interest, offers to take her on a tour via horse and cart. Throughout the tour, it appears to be broad daylight outside, as if it were early in the afternoon. Upon returning Meg to the hotel, it is dark again.
Peter had to put on a girdle to disguise his weight the first time he got on the rollercoaster. In the montage of photos at the end, he's on the rollercoaster with no girdle.
When Peter chokes on the rice cake, he screams. He should not be able to scream while his oesophagus is blocked.