Melissa Benoist's tattoos can be seen in adult Kara, when it has been clearly shown that needles cannot penetrate her skin.
Flashbacks set on Krypton and the opening credits show that Kara Zor-el does not have pierced ears. The adult, invulnerable Supergirl does.
Melissa Benoist has a divot scar between her eyebrows. But Kara Zor-El wouldn't have such a scar.