After the girls are "WOOHPed", and talk to Jerry, for one shot, Sam has a belly button. This is inconsistent with her character model, as usually no belly buttons are drawn. In every other shot, all of the characters are drawn without belly buttons.
In one shot when Sam, Clover, and Alex are driving a car, Sam is briefly drawn without hair.
The series is set in 1970 but the spa is from the 2000s.
A poster for Revenge of the Sith, The third Star Wars prequel movie is seen in 1977 but the movie wasn't released until 2005.