Following the fight in Lex's Mansion, Reign is defeated and Lena and Supergirl have a short conversation. Sometime later Lena and Kara are in a lift and also have a short conversation and all Kara does is wear glasses to hide her identity. She doesn't even change her hairstyle. Melissa Benoist who plays Supergirl/Kara has a small chicken-pox scar near her left eye that her glasses don't hide. This is one of many times that characters fail to see that Supergirl and Kara are clearly the same person. However, it is an acknowledged conceit that the glasses disguise just works, both for both Kara, and Clark Kent in the D.C. universe.