The title is a reference to capture the flag
Ravi's war paint includes the Greek letter (and mathematical symbol) pi on his left cheek.
Emma is shown wearing pink camouflage. Jessie notes that the purpose of camouflage is not to be seen. While pink is in fact highly visible to people (especially in a New York apartment), pink actually works well to avoid being seen by deer. Deer can see colors in the yellow-green-blue range but generally can't see red or orange (or pink).