The U.S. flag patch on Raven's space suit is backwards. While very few organizations (such as the Boy Scouts) display it as seen, the U.S. military as well as NASA wear the flag patch with the blue field towards the front of the wearer, as if they were facing into the wind rather than turning their backs.
When Raven lands on Earth and Finn locates her, he introduces Clarke to her. Ark has very limited population, everybody should have known one another, especially everybody should have known the celebrity kids, like Abby's daughter Clarke. Earlier also, several of 100 kids didn't know one another. the same age-group population would be even far less among the total population of the Ark, so most of these kids should have known one another.